Prefix - for MOST users I would recommend the 64 Bit version. This forum is principally a Gamers community and hardware enthusiast site. But there is case where 64 bit just is not practical.
malmental, your assessment that with 4 Gigs of ram more would be available in 64 bit operating system is correct. But “Also, 32-bit will not recognize all the ram you available.” is incorrect. 32 Bit operating system WILL recognize all 4 gigs of ram: However any hardware that maps memory will reduce the amount available to the operating system and programs. Typically with 4 gigs from 3 to 3.5 gigs will be available.
What affect this has is dependent on the user. If with 3.2 Gigs the user is not swapping memory in/out of the swap file then there will be no real noticeable diff.
Cassandra comment on will run most 32 bit programs is correct, what 64 Bit will NOT run is any 32 bit program that contains any 16 bit code (excludes the 2 high end win 7s that allow virtualization). For most that will not be a problem - For Me it would be a big issue at work. I do have Win 64 Bit on my main desktop and Vista 32 bit & XP 32 bit on by Back up desktop. On my two Laptops, both with 32 Bit Win 7 32 Bit. ALL computers have 4 gigs ram installed, and I can tell NO diff between 32 bit and 64 bit. In fact I’m thinking strongly of ditching 64 Bit and going back to 32 Bit. The only advantage with 64 bit is if I wanted to increase Ram above 4 gigs.