the only problem is I don't know what kind of harddrive would fit. I'd take it to a computer store but the part is probably twice as much as online. So i just wanna buy one that'd fit and take it there just to install it. Can anybody tell me how i'd know which part would fit? Would the same brand with 160GB fit?
THE PC I HAVE IS ASSEMBLED BUT HERE IS A FEW INFO.

Processor - Intel Core 2 Duo 6300 @ 1.8GHz
CPU Fan Heat sink and Fan Included
Motherboard Gigabyte 965P-ds3 Motherboard
Memory 3GB DDR II 800 Memory 240 Pin (Corsair)
Hard Drive Western Digital 80GB 7200RPM 8MB Cache Serial ATA
Optical Drive Lite-On DVD RW LDW-401 Sata Burner
Video nVidia GeForce 8800GT 512MB DDR3 PCI-E Dual DVI HDTV
Audio 6-channel HD Audio
Network Card Onboard 10/100 Network Card
Ports 4 USB 2.0 Ports, 1 Parallel
Case Rosewill Conqueror WSL Triple 120mm Fans Steel ATX Mid tower Computer Case with Side Panel

Power Supply 600 Watt Heavy Duty Power Supply