What Video Card should I Buy?

Hi, my computer has a 3.2 ghz amd processor, and a gig of ram. I want to play battlefield 2142 and maybe rainbow 6 vegas. I need a video card. I have a 500w power supply, and pci and agp slots. I do not have pci-e. I need a video card with 256mb ram built in. I have been looking, but I do not know if they have the pixel shaders 1.0 , 2.0 or 3.0, which i guess is important. I am looking to buy a cheap video card which will play battlefield. Thanks, Tim