Macbook Pro 15" hardware problem

Hey all,

I am having some issues with my Macbook Pro 15". The reason I am writing is because it is out of warranty and therefore I cannot send it to apple right away.

The issue:
After about 2.5y of having the notebook, it suddenly started showing white/grey/yellow stripes on the screen and started freezing. For a long while I couldn't start it again as it would just show me those stripes. Now from some reason it is working ok, but only for a short while.

I tried installing Snow Leopard on it, but it would freeze in the middle of the install. I tried running a test on the harddrive but it would freeze again. I am now running the longer Apple Hardware Test after the shorter one found no issues.

Did this happen to anyone? What is your guess regarding the problem? Is it the motherboard? hard-drive? Nvidia?

Help!!!
Thanks

Well I've seen this problem somwhere before. But the problem was for and old G5.

There were also stripes and constant freezes. In that case the graphic card was damaged due to overheating and after changing the graphic card the problem is solved.

Hope that helps.

Update, the longer Apple Hardware test froze on "Testing logic board"...