Here is the deal.
A PC I built for a friend, specifically for gaming a little over a year ago. Dual Core Athlon X2 7750 - 4 GB of DDR2 1066, Radeon 4870 512 mb. Running Windows XP.
He plays everything on it brilliantly, but he calls me the other day, he just got bit by the TF2 bug, got it durring the Steam sale, but it chugs and crashes. So I have it on my bench at home and I've checked the usual suspects. I cleaned the CCC and Drivers, re installed, no dice. I played with the settings, turning off Catalyst AI, then going into the game and turning graphics down, no dice. Then I checked the file integrity and defragged the game files through steam, no luck. I shut down all background applications and re ran the game, no luck. And when I say chug, I mean chug, like any firefight becomes this 15 fps slide show, its awful. There is absolutely no reason for TF2 to chug on this hardware, especially when this hardware checks out fine on every other application. Other games from the steam client load and play fine.
Icrontic TF2 guru's, any clue what I might be missing?