This is what I currently have:
CPU: AMD Athlon II 240 2.8GHz
Motherboard: ASRock K10N78M
RAM: OCZ 4GB DDR2
HDD: Western Digital Caviar Blue WD1600AAJS 160GB 7200 RPM
Integrated NVidia Geforce 8100
Integrated audio
Power Supply: A-Top ATP-AP700SC 700W
Case: GIGABYTE GZ-X5BPD-500
i have a very good gaming computer... and if you have the money i would recommend looking at the 1tb hard drive from western digital... and also the bigger the fan gets the quieter it gets...