I had a question from a lawyer I met at an airport yesterday. I told him I was the new Windows Guide, and was writing a lot about Windows 7. He was thinking about moving to that operating system (OS), and wanted to know whether or not to go with a 32-bit edition or 64-bit edition (About.com's Mark Kyrnin has a good breakdown on 32-bit vs. 64-bit computing).
I asked this guy about how he uses his computer, and he mentioned that he's a big gamer. That was a key piece of information, and I told him to definitely go with a 64-bit computer for his new one. That's because you can use so much more RAM, and Windows 7 takes good advantage of it. Without getting technical, more RAM means better performance for your OS and applications -- including games.
In addition, your computer won't get outdated quite as quickly. More computers being made now are 64-bit, and we're seeing more and more programs developed to take advantage of 64-bit speed. It shouldn't cost much more either. So my recommendation would be to go 64-bit, which will come pre-loaded with 64-bit Windows 7. Happy gaming!