32 or 64 bit Windows 7 professional for this build?

Windows 7 makes a 86X folder on your C: drive for 32 bit applications and a regular "program files" folder. I switched from XP to Win 7 64bit and everything works correctly. One time ago there was capability issues, but that was with Vista. A 64 bit system recognizes over 4 gigs of ram and utilizes quad core. Other than that I do not know what its good for.