It seems to me, that no one has yet replied to the original question: "should he change his CPU"
>From my point of view: no. do you use some unix? if not you'll not use the 64bits. Even if you use it, it's not always true that a 64 bits COU is faster than a 32 one, in some cases it's slower. Then: His "dual core Athlon" is not a dual processor machine, it's a processor with two cores (I suppose they'll work in parallel doing some operation.) Don't know if windows can use it, though, but I think it's something the OS doesn't even know it is there. bottom line: save your money for some trip. ;) Danilo.
