Without question, the video card is the number one most replaced part in my pc. I probably replace it with a mid-range card ($200) every other year. As I stated earlier, this is a problem right now as there aren't any good values at that price point. Oh, and get the biggest, baddest PSU you can afford. Note that doesn't just mean wattage, it means get one that's stable and reliable. I have an Antec trio 660, it's a rock and will probably last me through several iterations of upgrades. The only reason I got it to replace my old Antec (which is still running in my htpc), though was because of the new ATX specifications.
If you're dead set on getting an AMD chip, I urge you to wait until their new chips arrive. Otherwise you're throwing away performance. Simply, the architecture is at it's life's end and can't compete in any way except for price point. It's funny, because just a short time ago, the exact opposite was true, AMD had the cutting edge architecture and Intel was trying to squeeze performance out of the dying platform (P4). Heck, if you wait a few months, I bet there'll be some nice video cards out there that will actually perform well for around $200.
