I've been three boxing warlocks for a few months now, and I just started some shamans, and it's incredibly fun, but I feel I need to upgrade my computer a bit. I still get some lag and low (less than 10) frame rates out in the middle of nowhere, and most cities are just impossible. I just walk my characters through one at a time. And since I've been meaning to upgrade anyways, I figure that's a good excuse.

Now, even though I spend between 4 and 14 hours a day at a computer, I somehow managed to not know too much about them. So what exactyl should I be looking for and what's important? I already have monitors and various input devices (mouse, keyboard, N52, etc) covered, but I'm looking to get a whole new set up otherwise. Looking at anywhere between 500 and 1000 dollars for the whole thing.