Ok as i suspected in my previous post, it was my motherboard which was at fault.
I got a new one and installed it. That was the easy part.
Now when i start the computer it does boot up and post but when it get to the windows start screen and blue screen quickly appears and the computer restarts it self.
I have tried to repair the installation using my windows vista cd but i still get the same problem.
Any advice what to do next?
Thanks in advance.