Personaly, I would say Vista64...Vista86 is only arround because of the eeePC & microsoft wanting to capitalize on old systems that cannot run vista well anyway. Windows 7 is just the next windows. It is not the big leap seen going from XP to Vista, it is more like the leap from 2000 to XP. Windows 7 is right around the corner...but it will not be ready for about two years (microsoft usualy gets an OS right about a week before they release the next one) By all means, try linux (or Solaris) if you never run games, and you don't need ActiveX for anything (some online business apps require ActiveX), it should do just fine.
and non-64 bit CPUs, such as earlier P4s, Athlon XPs, and the original Core Duo mobile processors (the latter aren't that old, mid-2006)
