keithp wrote:I have an Asus P4P800S-X motherboard with dual Pentium4 2.8GHz processors.
Those are 64bit processors. Quick test: burn a 64bit Ubuntu CD and try to install it. If your CPU is not 64bit, it will refuse to install and tell you why.
But do you NEED a 64bit OS or is this a "gee whiz look what I can do" sort of thing? Unless your hardware is new, your configuration solid, and your hardware supported 100% by native kernel modules, I'm leery of 64bit right now. On the right hardware, it can be great. But the right hardware includes gobs of RAM. The 32bit-generic kernel can't recognise more than 4gb. The 32bit-server kernel and the 64bit-generic kernels can both address more than this. So do you need a 64bit kernel to address gobs of ram? Not necessarily.
64bit on a desktop. Laptop? May be capable of 64bit, but wifi and suspend/resume are the gremlins you face and too many of the wifi solutions involve ndiswrapper and Win98 drivers.