Do your systems contains 64-bit processors? There is a terrific little utility that will answer the question instantly - Securable from Gibson Research Corporation. It is a zero-install program, which means you simply run the EXE file from wherever it is. There is never a need to uninstall.
Steve wrote the program to determine whether a processor supported the three critical hardware capabilities needed to maximize system security, hence the name. I've used it primarily to check "bittedness" and the status of hardware virtualization (whether I could run VMWare or Virtual PC 2007).
Whether you can move cleanly to a 64-bit system involves more than just having the right processor. 32-bit drivers do not work in 64-bit Windows. Some application software may not run. But without a 64-bit processor, you definitely can't make the move.