I have the opportunity to buy Win7 Ultimate either the 32 or 64 bit version for less than $50. A legit copy. Do I buy the 64 bit version to be a "little" future proof or stick with the 32 bit version? Not really gaming anymore..more just everyday surfing and such.

Current setup:
Athlon 64 3200
2 gig PC3200
320 HD (win 7 will go on this)
80 (XP already installed but with keep as a dual boot machine)

Thanks