LOL, you so under-estimate this game. If it actually runs at that, I would almost give you money. There is no way a 7800GT is going to pull that off, we are talking about Unreal Engine 3!
Maybe its the Source engine you are thinking of....HDR...4x AA...still 50 fps.
Unreal Engine 3 will run at a slide show at those settings on a 7800 series card. Turn off the HDR, AA, soft shadows, and lighting to low, textrues to medium, and you might have a playable game at 1280x1024.