Answer to your first Q Yes your PC will run XP64, I've run it with a Sempron 2800 (Socket 754) The big question is though, how much of your Hardware supports 64bit windows. For instance, there is no driver for my modem and the Mfr tells me there is not going to be so that would mean me buying a new PCI, or whatever non USB modem that does support it. Presumably XP64 will run faster than 32bit but that's just the O/S. I believe graphics and the internet will not. There is not a lot of 64bit software available at present as far as I know.