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Some people routinely advocate using the DOS command FDISK /MBR to remove viruses that infect the hard disk's master boot record sector. However, this may not successfully remove such a virus, and it can be dangerous advice to follow.

FDISK is a DOS program ordinarily used once to partition (divide) the hard disk's space into individual drives for formatting. Once the disk is partitioned and data is stored on the drives, there should be no need to use the FDISK command again. In addition, if it is improperly used, there is a risk of data loss.

When DOS 5.0 was released in 1991, the /MBR switch was added as an option. However, since it might not be safe, Microsoft elected to leave it undocumented (not listed in the manual). Nevertheless, some people discovered that the FDISK /MBR command can be used as if it were a utility tool.

BITS, BYTES, KILOBYTES, MEGABYTES, GIGABYTES EXPLAINED

Let's begin with the itty bit (short for binary digit), the tiniest unit of information handled by a PC. Eight bits make up a byte, which typically represents a letter or a digit. You'll see measurements in kilobytes (1,024 bytes), megabytes (1,048,576 bytes) and gigabytes (1,073,741,824 bytes). The more gigabytes of storage a computer has, the better.

In decimal systems, kilo stands for 1,000, but the computer world is based on a binary system of twos instead of tens, so kilo stands for 1,024.

8 BITS = 1 BYTE
1 BYTE = ONE TEXT CHARACTER (it takes 8 bits to send one text character)
1024 BYTES = 1 KILOBYTE (1KB) frequently abbreviated as just K
1024 KB = 1 MEGABYTE (1MB) (1,024 X 1,024 = 1,048,576 bytes, or 1MB)
1024 MB = 1 GIGABYTE (1GB) (1,024 X 1,024 X 1,024 = 1,073,741,824 bytes, or GB)
1024 GB = 1 TERABYTE

Usually, when written out, the following abbreviations apply:

KB = Kilobyte or KBS Kilobytes per second
Modem connections speeds are measured in bps (Bits per second)
For example, a modem connection at 44,000 bps = 5,500 KBS (Kilobytes per second)
So to down load a MB (1024K) at 44,000 bps would take approximately 3 minutes & 7seconds.
at 26,400 bps the same MB would take 5 minutes&11 seconds.

The usual maximum speed of the V.90 56K modem is really 53K download and 33.6K upload.

Modem connect speeds vary widely due to the quality of the phone line, if you are located more than 18,000 cable feet from the telephone co. office, (3 miles or so) and served over plain old copper telephone cables, rarely are connections greater than 26.4K or 28.8K achieved.  Your reported modem speed, i.e. 26,400 etc, is in Kbps (Kilobits persecond).   When you download and get a message that says something like 2.9, it is in Kilobytes (X 8 =) 23.3 Kilobits.   Rarely will you actual download speed match the carrier or connect speed.

Some Web sites store information in a small text file, called a "cookie," on your hard disk.

Cookies contain information about you and your preferences. For example, if you inquire about a flight schedule at an airline's Web site, the site might create a cookie that contains your itinerary. Or it might only contain a record of which pages within the site you visited, to help the site customize the view for you the next time you visit.

Only the information that you provide, or the choices you make while visiting a Web site, can be stored in a cookie. For example, the site cannot determine your e-mail name unless you choose to type it. Allowing a Web site to create a cookie does not give that or any other site access to the rest of your computer, and only the site that created the cookie can read it.

Internet Explorer is set up to allow the creation of cookies; however, you can specify that you be prompted before a site puts a cookie on your hard disk, so you can choose to allow or disallow the cookie; or you can prevent Internet Explorer from accepting any cookies.

You can specify different settings for different security zones. For example, you might want to allow Web sites to create cookies if they are in your Trusted sites or Local intranet zone, prompt you before creating cookies if they are in your Internet zone, and never allow cookies if they are in your Restricted sites zone.

MS Knowledge Base Articles about cookies & MS Internet Explorer:
Q278835 - How to Delete Cookie Files 
 

FAT-32 only available in Windows 95 OSR2 and All versions of Windows 98/ME.  Original release of Windows 95 only supports FAT-16 which limits hard disk partition size to 2-GB.  Many 486 systems only support partitions up to 511MB.  The  Larger Partition size means larger cluster size, and larger clusters mean more wasted disk space. 

Hard_disk Management from MS Knowledge base
Q255867 - How to Use Fdisk and Format to Partition or Repartition a Hard Disk 
Q153550 - Hard Disk Limited to 8-GB Partition 
263044 - Fdisk Does Not Recognize Full Size of Hard Disks Larger than 64 GB
314463 - Limitations of the FAT32 File System in Windows XP
309000 - How to use Disk Management to configure basic disks in Windows XP
315688 - How to Locate and Correct Disk Space Problems on NTFS Volumes in Windows XP
File and partition size limitations using the FAT32 file system. From http://support.wdc.com/archive/ KB FAQ's 10/31/07

Maximum Sizes on FAT32 Volumes
A FAT32 volume must have a minimum of 65,527 clusters. Windows XP Professional can format FAT32 volumes up to 32 GB, but it can mount larger FAT32 volumes created by other operating systems. Table 13.6 lists FAT32 size limits.

Table 13.6   FAT32 Size Limits

Table 13.5   NTFS Size Limits

Size Limitations in NTFS and FAT File Systems

Each file system supports a maximum volume size, file size, and number of files per volume. Because FAT16 and FAT32 volumes are limited to 4 GB and 32 GB respectively, you must use NTFS to create volumes larger than 32 GB. If you use FAT16 or FAT32 in computers that start multiple operating systems, you must note the following size limitations:

• FAT volumes smaller than 16 MB are formatted as FAT12.
• FAT16 volumes larger than 2 GB are not accessible from computers running MS-DOS, Windows 95, Windows 98, Windows Me, and many other operating systems. This limitation occurs because these operating systems do not support cluster sizes larger than 32 KB, which results in the 2 GB limit.
• In theory, FAT32 volumes can be about 8 terabytes; however, the maximum FAT32 volume size that Windows XP Professional can format is 32 GB. Therefore, you must use NTFS to format volumes larger than 32 GB. [Exception] However, Windows XP Professional can read and write to larger FAT32 volumes formatted by other operating systems. For example, a drive or partition formated with FDISK..

Maximum Sizes on NTFS Volumes

In theory, the maximum NTFS volume size is 2⁶⁴ clusters minus 1 cluster. However, the maximum NTFS volume size as implemented in Windows XP Professional is 2³² clusters minus 1 cluster. For example, using 64-KB clusters, the maximum NTFS volume size is 256 terabytes minus 64 KB. Using the default cluster size of 4 KB, the maximum NTFS volume size is 16 terabytes minus 4 KB.

Because partition tables on master boot record (MBR) disks only support partition sizes up to 2 terabytes, you must use dynamic volumes to create NTFS volumes over 2 terabytes. Windows XP Professional manages dynamic volumes in a special database instead of in the partition table, so dynamic volumes are not subject to the 2-terabyte physical limit imposed by the partition table. Therefore, dynamic NTFS volumes can be as large as the maximum volume size supported by NTFS. Itanium-based computers that use GUID partition table (GPT) disks also support NTFS volumes larger than 2 terabytes.

(Note:  Clicking on any of the sound WAV files below will play the corresponding 2 second sound clip.  Each clip is 50KB to 60KB in size so give the clip a chance to download.  If play of the sound is jerky the first time, replaying it a second time should help.)

A high-pitched whining sound (bearings.wav) could mean your hard drive's bearings are going bad. Relatively speaking, this is good news; you may actually be able to rescue your soon-to-be-stranded data. If your operating system loads and you're able to move files off the hard disk, do so immediately.

If you hear sustained clicking noises, you probably won't be able to access the hard disk at all, and your operating system most likely won't load. A pause-click, pause-click sound (cycleclick.wav) indicates that your drive's read/write heads are trying to orient themselves. The drive has probably sustained some damage, and you've likely lost some data. Continuous, rapid-fire clicking (excess.wav) is an ominous sound for any drive.

In either case, your chances of recovering your data manually are slim. Don't keep turning your system on and off in hopes that your hard drive will finally catch, or start up, one last time; it won't.

Any grinding or scraping sound (grind.wav) is another sign of serious trouble. Your hard drive's read/write heads are in contact with the disk's media surface--where the data is stored. Shut down your drive immediately; the longer it runs, the more data you may lose.

A good basic virus_defense strategy, By Don Brohm:

1.  Keep your PC Antivirus software up to date, at least weekly.  Not running antivirus software?  You are asking for trouble!  

2.  NEVER open attachments that can launch a program or service.  The most common of these, identified by their file extension, [the two or three digits after the "." (period)] are:  .exe, .vbs, .js, .pif, .zip, and .scr files.  NEVER, no mater who they are from, unless you requested the file, or received a prior email or phone call informing you the attachment was coming and what it was.  FOR A MORE COMPLETE LIST OF FILES, BY EXTENSION, THAT CAN CONTAIN HARMFULL INSTRUCTIONS SEE BELOW

3.  Don't use CHAT software as viruses/worms spread via chat sessions.  Personal networking sites such as Twitter and Facebook can be risky also.

4.  Update windows by going to http://windowsupdate.microsoft.com/ at least once a month, run "EXPRESS" and install all "High Priority or Critical Updates".

5.  You should have at least the built in Windows firewall turned on.

6.  If your computer is connected to the internet through a router, you have more protection from malware attacks, as your PC is generally invisible from the internet.  Test your pc's ability to be hacked from the internet at Gibson Researches Shields up page.  www.grc.com click on SERVICES, then SHIELDSUP!

7.  Also re-evaluate the need to activate file sharing, it is preferable to turn off file sharing.  At a minimum any shares should be individual folders, not complete drives, and should be password protected. 

8,  With XP, as a minimum, download Microsofts free Defender, which is by default part of Vista and Windows 7.

FILES WITH THE FOLLOWING  EXTENSIONS CAN LAUNCH VIRUSES OR WORMS
Executables:  ---------------------------------------  .com, .exe, .bat, .cmd
Scripts: ------------------------------------------------  .ws, .wsc, .wsf, .js, .vb, .vbe, .vbs
Other Service Launching Extensions: ---  .pif, .msi, .hta, .scr, zip