Well, I really have no idea about how to approach upgrading computers, so I just kinda picked a graphics card.
I was considering buying a new computer, but going to see if an upgrade was possible. Then again, with Windows 7 out now, it's all the more reason to just buy a new computer. Meh, I got five good years out of this thing, thanks for your advice.
If anyone else has suggestions, feel free to express them.