Getting to make actual use of 4-gigs of RAM is an advantage.
Crysis 64 having better mountain textures is an advantage
This mod I've been playing for HL2 requires 64-bit and 4-gigs of RAM, but it's freakin amazing http://halflife2.filefront.com/file/Fakefa...0_Part_16;88111
32-bit programs and games run just as good, when I compare to running them in 32-bit XP, since 64-bit CPU is backward compatible with x86, I don't think any emulation is involved