I have the Windows XP32-bit install disk, but running it greys out the "Install Windows XP" label. Could someone post info on formatting a single harddrive computer with XP64-bit? I don't know how...

You are supposed to boot from the CD, not run it from within Windows - that's only for upgrading and you can't "upgrade" XP64 to XP32.

Make sure you have enabled booting from the CD in the system BIOS, press any key to boot from the CD when you are told to. You need a drivers floppy if you are using SATA.

Choose to install Windows, delete all the partitions (unless you want to keep some data), recreate them if you want something else than a single partition spanning the whole hard disk.

I'm using SATA, but I've never even had a floppy. I have a spare drive, I know how to install it, but what do I need a driver floppy for? I have all of the original drivers for XP on cds.

I guess the problem was, that I couldn't boot from CD. I never had to enable booting before. Thanks for that.

You need a floppy with drivers for your SATA controller on some motherboards. You boot from CD, press F6 to add aditional drivers during the initial stages of the windows boots CD (it say press F6 on the bottom of the screen) when asked if you want to add additional drivers you follow the instructions, this is what you would have done if you actually had a floppy in your system. If you are lucky you dont need a SATA driver on a floppy, the BIOS lets you "emulate" IDE. Try and boot from the CD, if the windows install sees you drive and the partitions on it, your ok, if the system tells you it could not find a hard drive, you need to get a floppy

EDIT:
You need to have the drivers for the SATA on a floppy, because the XP install only lets you add drivers from that, a floppy. (after all, XP is quite old nowadays)

You can intigrate the SATA driver onto your XP install disk with tools like nLite, but thats a diffrent explanation to cover.