Can I install xp pro over xp home?

like they all said, sure..but over xp home? wipe your drive entirely, either by formatting it, or with a third party disc wipe app. Third party disc wipe apps work independent of an OS, have their own boot script, and can completerly erase and partition your hard drive before you start windows install. Then do what's known as a clean install of xp pro. Supposedly, lore has it, the source kernel in xp pro is thought to be a more stable code than the kernel used in xp home, leadiing to fewer crashes, hangs and fatal errors.

I'm pushing the clean install, cuz there's less chance of old files popping up from hidden directories or some such nonsense.

if you have a xp pro with an xp pro key

then yes

the OS uses the same drivers as xp home

to my knowledge if you just put in the disc for an upgraded version it will install as well as delete the old program

Just reformat your HD and install the software.