[locutus2002]

Basic troubleshooting:

I'd replace the CPU first (should be 1 yr no questions asked)
I'd replace the memory second (should be lifetime garauntee)
I'd add a fan to the chassis. (its possible that the video card is heating everything up if its high performance)
Then I'd replace the motherboard
Then I'd replace the powersupply.

Overall you're better off buying a premade system if you're going to tweak it because they actually look at things like heat dissipation.

I have dual video cards in a docking station. My 4 year old thinkpad is disposable.