Sheesh, my 6 month old nVIDIA GeForce 7900 GS card died on me yesterday. I was installing Ubuntu on a spare hard drive in the tower and all of a sudden there was a loud 'pop' and a bright flash then the screen went black. The rest of the PC was still running.
The fan has seized up (well, almost. Its very hard to turn it). That's what caused it to overheat, of course.
You can see where its burnt, like a sort of black gooey stuff there. Lucky I've kept my 4 year old ATI Radeon 9600 card, I'm using that on the main PC at the moment. I thought I'd lost the receipt but I've found it, thank goodness. Back to the computer store it goes in the next day or two.