Don't quote me on it but I don't think the 8500GT is too good of a card. It'll run BF2.. but wouldn't really keep up with the newer games that are going to be coming out. Also for BF2 you want 2gb of ram. I only have 1.5gb and that's one thing that keeps me from playing, too much damn loading time.
Make sure you don't go AGP if you're going to spend money on a whole new PC. PCI Express is faster and easier to find cards for.
If I were to buy a budget friendly gaming pc any time soon I'd most likely find a Barebones deal at Tigerdirect
here Is where I'd start, you'd still need a monitor though, so figure $150-$200 there if you want a decent 19" LCD. Find one without the OS included.. and you can buy a copy of XP! (And watch out.. some of those barebones come literally bareboned.. and others come with almost everything you need.)