Hi, sjh001 -
Did you get anywhere with this? I just re-installed W2K a coupla days ago. You say you've got the W2K CD? Just go into your BIOS, make sure to set your CD drive as the first boot device (or even the second, so long as the computer looks there before going to the hard drive), then hit whichever keys it takes to save the change. If you're not sure about this, go back into BIOS when you think you're done and check to see that the change took. It's fairly easy to not make a change when you thought you did.
O.K., so the computer will try to boot from the CD drive before the hard drive. Toss the CD in the tray, restart the machine, and just follow the steps that the Windows CD takes you thru. The way I remember it, Windows loads a whole bunch of basic drivers against a blue background, and then the background goes black. You don't get to the "format" choice until several steps into the CD menu. Windows will say something about detecting a previous copy on the main partition (if that's where it is) and will ask if you want to repair or re-install. If I remember correctly you choose re-install and that's when it asks you about formatting. The first few times I did this I thought I'd screwed up somehow. Another important piece of advice - I keep a binder with records of all this stuff handy. Have that binder open to a new page, with the date written in on the top, and make a note of EVERY step you take.
My re-install the other day was on a hard drive that had W2K on it, so my experience should be identical to yours.
You know what? When you're done, you oughta just turn right around and do it again. Before loading chipset, video, modem, sound, etc. drivers, just go right back and re-install again. I guarantee you, practicing a few times will make you feel much more confident. BTW, do you have acopy of the W2K roll-up that M$ put out a coupla months ago? A friend with broadband downloaded the whole mess and burned it to a CD for me. After installing W2K (unless of course you have broadband and don't care about the huge download) run the roll-up package and then you'll have fewer updates left after that.