Can anyone tell me if my processor is 32 bit or 64 bit?

I'm looking into upgrading an old desktop that currently runs Windows XP Media Center Edition 2005 with windows 7 and everywhere i look i get a combination of 32 bit and 64 bit answers. I have an Intel Pentium 4 processor 630 with 3.0 GHz CPU, 800 MHz FSB, 2mb L2 cache.