What kind of stores say they dont sell 64 bit OS's anymore??
The fact is, 64 bit is the future, and i'm going to say that within a year if you dont have one, you are going to be behind the times. One of the major facts that I think is pushing 64 bit OS's is the ability to have over 4GB of RAM, and be able to use it.
As for those games, i've played most of them on Vista Business x64 and they run fine, except BF2/2142 Demo had issues with Punkbuster, but I believe it was fixed in either a patch or by running it as an admin.