William, I just noticed your processor family, Sempron. Not one made for gaming by AMD. The Athlon, Turion and Phenom are better for gaming unless you go with totally new. Buy a new top of the line motherboard/CPU setup and build from there as that is the main control of your system. If you have an old one no matter what graphics, HD or RAM you use it will be limited by the CPU. Plus if you go this route you know you have assurance your PC can and will upgrade easily for a while from there. Newegg, Tiger and pricewatch are good places to get parts from to build cheaply.
This town is infested with killer cockroaches .. repeat .. killer cockroaches !!