All C2D machines are 64 bit. Your friend is also wrong on the 64bit part showing in windows, unless you are speaking of Win XP Pro 64bit (slightly different OS).
If you are really concerned, just go herehttp://ubuntu.cs.wisc.edu/pub/mirrors/l ... ases/edgy/
Download a 64bit AMD64/EM64T Desktop CD disc, and just let it run. It will work as a "live" disc, and go to a working desktop (wont install anything until you specifically tell it to). As the software only runs in 64bit mode, if it works... your machien is 64bit, if it doesn't you have problems
Mmm actually not strictly true, a lot of the first core 2s were 32Bit Processors with 64Bit instruction set interpreters - I.E. they could effectivly run 64 Bit but they translated it into 32 Bit first.
However I believe that they started running true 64Bit Core 2s, I'm not to sure on that one.