backup! if u can afford to loose ur data dont worry then. and of course u wont need 500gb, unless it is full. and event viewer will tell you what is wrong. usually a chkdsk will resolve some/most issues from error msgs like that in windows.
System Manufacturer/Model Number Windows 7 Ultimate 64-bit OS Windows 7 Ultimate N 64-bit CPU AMD Black Edition - AMD Phenom X4 2.5 GHz Processor Motherboard Bio Star Memory 8GB DDR2 800MHZ BRANDED Graphics Card Palti NVIDIA GeForce GTX 460 Monitor(s) Displays 3D 23.6" & 22" Screen Resolution 1920x1080@120Hz
PSU OCZ 600W StealthXStream PSU, PowerWhisper, Active PFC Hard Drives 313GB SAMSUNG SAMSUNG HD321KJ Internet Speed 22793