do you have to use the 64bit of xp to have a 64bit processor?
thanks in advance
No, regular windows xp sp2 (32bit) can be used. Amd64 cpus can run 32bit and 64bit os's.( I assume intel is the same with the 6xx series).
64bit gives you access to more ram(than 4gb), IIRC, and some apps can be made to run better in 64bit mode.