Fast help on low budget build

APPROXIMATE PURCHASE DATE: when someone recomands a nice rig i will order the parts

BUDGET RANGE: 500-550$

SYSTEM USAGE FROM MOST TO LEAST IMPORTANT: gaming, surfing the internet, school stuff

PARTS NOT REQUIRED: keyboard, mouse, monitor, speakers, OS , DV burner

PREFERRED WEBSITE(S) FOR PARTS: http://www.emag.ro/ , i know its not english but it has the best prices here if you want translation help , ask

COUNTRY OF ORIGIN: Romania

PARTS PREFERENCES: since its a fast low budget, AMD-ATI

OVERCLOCKING: Maybe on the video card

SLI OR CROSSFIRE: Maybe , not sure

MONITOR RESOLUTION: 20" Wide 1600 X 900 ( i know , crappy )

ADDITIONAL COMMENTS: i wanted to spare some money for a Intel-Nvidia build but since my current pc started crashing today i decided to get one fast , i would like it to be able to play games like Diablo III , Battlefiel Bad Company 2 , NFS Shift and the new Hot Pursuit , Aliens Vs Predators etc. but i will play on low detail and 1024 X768 res