I would say 32-bit SP2 at the moment, as it has the most support of all of them (drivers, apps) and would be most suited to gaming at this particular point in time, if that is in fact what you plan on using it for. 64 bit XP would only allow you a few advantages over 32 bit XP at this point, mainly with things like more RAM allowed, etc. Where you lose when going to 64 bit XP is in driver support, and even application support sometimes. So, it's your choice, but I would recommend 32-bit SP2.
![[H]ard|Forum](/styles/hardforum/xenforo/logo_dark.png){kind=logo}