Hi naelcm.
You cannot "upgrade" to a 64 bit version of Windows from a 32 bit one: if you have a 32 bit version of Windows and want to install a 64 bit one, you have to install it from scratch (it would be the same for moving from 64 bit to 32 bit), provided
that you've all the necessary 64 bit device driver your computer needs and that all thr programs you use can be installed end executed in a 64 bit OS.
If you need to buy a 64 bit CPU, check the technical specifications and look for an explicit indication about the supported instruction set (32 bit or 64 bit).
Bye.
Luigi Bruno
MCP, MCTS, MOS, MTA