You can research Intel processors here:
http://www.intel.com/products/proces...cts_processors&
As for the laptop with a 64-bit processor: programs need to be written specifically for 64 processors, as well you'd need to be running XP 64-bit OS first. If you satisfy both those needs (you have a 64-bit OS and 64-bit applications) then you'll make good use of the 64-bit processor, if not then you're paying extra for functionality that sits idle.