It's not as simple as that... Because it's 64bit, it also USES more memory for each app that in 32-bit would use less.
As far as actually recognizing that more memory is there, does it still limit itself to 2GB max for any single program like XP does? I thought somebody mentioned that in regards to 64-bit, but I can't be sure.
See you're running a 32-bit app on a 64-bit system. May seem like you get more ram, but you're not seeing any benefit from it.