xp home or xp pro 64 bit

I would strongly encourage you not to rely on Win64 as your sole operating system, even if there are drivers available for your peripherals (printer, scanner, etc). There is no reliable virus protection that works with Win 64 period, no matter what you read. There is no reliable CD-DVD writing software that works reliably with Winn 64. There is no packet writing software period. There are many incompatibilities between 32 bit Windows programs and Win64, including some not so subtle issues with MS Office. There is no video editing software that works reliably with Win 64. Photoshop CS2 works pretty well along with Epson printer and scanner drivers, but that has been about it in my experience. However I could not use my monitor calibrator because there are no drivers for Win 64 so I installed the profile from WinXP. This is called a kludge, one of many you have to create to be able to do real work with Win64. Why bother? One of the reasons for the variable successes people have using Win64 has to do with the unreliability of the basic motherboard drivers, both for Intel and AMD compatible chipsets. Win64 should only be used for tinkering with in a dual boot system. If you are one of the lucky ones for whom it works reliably then knock yourself out. You will not see any real world performance gains however and will inevitably run into serious instability issues with some software-hardware.