This revives a rather old thread, so some of the earlier stuff needs to be ignored perhaps.

Advice already given about making sure you have boot disk(s) and program reinstallation disks still apply.

Win95 and Win98 were not able to use hard drives over a certain size, because in the original "FAT" format they use only 16 bits to identify the location of the cluster where the data is written. There are a limited number of numbers you can write with only 16 bits available, so you can have only a limited number of clusters in use. If you set up a large disk with a single partition, the disk should work okay, but you can only use the first "n" clusters, and the rest of the disk is wasted.

Later versions of Win98SE can use FAT32 hard drive layout, which increases the size you can use on a drive since there are a lot more numbers available, with 32 bit word length, to label which cluster contains a given chunk of data. I haven't used Win95 for so long I don't remember, but I don't believe it is "FAT32 capable."

Some larger hard drives come with "overlay" drivers/controllers that allow larger drive sizes to be used without partitioning; but that's sort of another story.

Creating a new partition simply puts a "marker" on the disk that says "start a new disk here." The "marker" includes a new File Allocation Table (FAT), a backup copy of the FAT, and usually a "nearly empty" boot sector. The new FAT records where stuff is in the new partition.

The space up to the marker is your new C:\ (assumed, it could be your D:\, etc.) drive, and the space above it is your D:\ (or next available letter). You can have as many partitions as you want on a physical hard drive - up to where you run out of letters (at "Z") to identify them. Obviously, other kinds of drives may also use some of the the 24 letters available, after A:\ and B:\ are "reserved" for floppy (removable media) kinds of drives. (A:\ and B:\ shouldn't be used to identify hard drives - it confuses your BIOS.)

Each "partition" acts as if it is a separate hard drive, as far as your operating system is concerned. For clarity, call a partition "logical drive x" to distinguish it from "Physical Drive 1 containing logical drives C:\ thru N:\."

On "primitive" systems, or using the "primitive" (DOS) method, you run FDISK.EXE to set up the partition sizes. If you use the DOS version appropriate to your OS, it should offer choices of the drive layouts (FAT, FAT32, NTFS) the system the DOS version came from can use.

After you've set up the partitions, you need to FORMAT each of the partitions. This, of course, erases everything on the disk. The FORMAT operation puts a marker at the beginning of each cluster, numbers them in order, and marks them as "empty."

There are programs available, generically called Partition Managers, that allow you to create, remove, resize, or change type of partitions without harming existing data, as long as you have sufficient free space on the drive to handle the "bookkeeping" involved. "Partition Magic" is one that's been around for a while, and reports have been good on recent versions. There are several others that have been reviewed favorably. I haven't needed to use any of them, but others here appear to know them.

One of these programs would be helpful if you have a lot of stuff that you'd have to put back, and you can sometimes avoid reinstalling the system.

Note that although the Partition Managers all say they can move the partitions around without damaging data, the all also say BACK UP ANYTHING CRITICAL FIRST. If you get a Partition Manager for an immediate use, the backup is recommended until you get some experience with the program. Once they're more confident, many people don't bother (everybody needs a few thrills); but you do need to be sure that it stays on the road the way you drive it before you omit the step.

All of the above applies if the purpose for adding a partition is to add another OS. A difficulty sometimes arises that for some combinations of multi-OS installations, a particular one must be installed FIRST. The root folder/directory for each OS must be in a separate partition, and the OS files should usually all be in the "root" folder for the applicable OS. You will need some sort of "multi-boot manager," so you should consult documentation on the one you choose for how to reinstall and get both OSs to work. Others here with multi-boot systems will possibly advise.

A possible complication with WinXP already installed is that many machines with WinXP on will have the hard drive already converted to NTFS format. Your Win98 OS will NOT be able to read anything in that partition, so any "shared files" - including programs - will need to be reinstalled in a FAT32 (for Win98SE) partition, or possibly even a FAT (for Win95) partition.

Some of the Partition Managers do claim to be able to change an NTFS partition back to FAT32 without damaging anything. WinXP will run from a FAT32 partition, but it's not really the best setup for the OS.

John