FPS games at 16x10. I wouldn't bother with the 4870, get the 4850 instead. The CPU you picked out is good, but with the money saved you should be able to get a quad. You should be able to get the 9950 for the same price, and at 16x10, you won't notice the difference.
I would make sure your motherboard can use the CPU, and if the video card is still under warranty get it fixed and keep it as a spare or sell it.
Good choice on the video card, VisionTek is the only ATI card I would buy.