Helo i try to play a game and i get nmi memorry parity error blah blah, with a blue screen.

There are number of things that can cause an error like this. Faulty memory, a bad harddrive, a failing motherboard, or a corrupt OS.
If you get this error every time you power on your PC than follow the below steps
It probably meant the installation itself was corrupt, not the disk you were using.

To test your memory try Windows Memory Diagnostic Test
http://oca.microsoft.com/en/windiag.asp

The Windows Memory Diagnostic tests the Random Access Memory (RAM) on your computer for errors. The diagnostic includes a comprehensive set of memory tests. If you are experiencing problems while running Windows, you can use the diagnostic to determine whether the problems are caused by failing hardware, such as RAM or the memory system of your motherboard. Windows Memory Diagnostic is designed to be easy and fast. On most configurations, you can download the diagnostic, read the documentation, run the test and complete the first test pass in less than 30 minutes.

Or you can try memtest

To test your hard drive for corrupt/bad sectors find the manufacturer of your hard drive and run their Hard Drive Diagnostics Utility.

This will give us a foundation to work on and will (should) eliminate two possible sources of your problem.