I'm fairly sure you can't run a 64-bit app on a 32-bit OS. What 64-bit means is you can access a larger quantity of RAM for the program. If you've got a 64-bit system, sure, install Maya 64-bit. Out of curiousity, how much RAM do you have?

I run Win 7 64-bit and Maya 2009 64-bit, seems good for the most part.