Mobo: Asus p5b or gigabyte ps3
Cpu: e6300 (e6400 if you can afford)
Ram: g-skill (2x1gb)
hdd: Seagate barracuda 7200.10
Vid card: 7900gs/gt
psu: any good brand e.g. antec fortron ocz
case: whatever you like the look of with a 120mm intake and atleast 120mm out take
heat sink fan: scythe ninja (for over clocking so that you can increase performance without costing more