Suggestions for the first PC game on my new rig?

I built my new rig about a month ago, and I'm ready to start gaming on it. I've got CS:S already, but it's starting to get bland. I want something that I can buy from a store, not online. I want it to be cheap. $30 is nice, but I can go higher if the game is good. I have FO3 and GTA IV for my 360 already.

My rig specs are in my sig, so I'm pretty sure I can run anything.

I can't see sigs kjghs

here ya go :D i would recommend the orange box and left 4 dead for some good pc gaming fun and for the graphics get crysis warhead and crysis as they r the most advanced pc games atm.some other good looking games are far cry 2,call of duty 4, and unreal tournament 3 altough no wherenear the level of crysis running at veryhigh settings.