My 8800GTS just died last week. Green lines appeared on the screen, game crashed, then windows crashed causing a BSOD. It was heat related because it kept shutting down and the driver kept crashing. The card was HOT to the touch.
As for the AMD to Intel thing. Your going to notice a big difference if your upgrading from older hardware. Even with AMD's top of the line hardware, it wont equal an Intel. But that's not what AMD aims for. They also have considerably less money then the Juggernaut that is Intel. They aim to please the user that wants the most bang for the buck. I just upgraded from an Athlon-64 5600X2, to a PhenomII 955. Huge difference in performance.
Also one more thing to worry about, Intel has teh habit of changing sockets every 6 months or so. Great example with the i7's. Intel has just released a bunch of i5's that use a new socket because these new chips do away with the Northbridge on the motherboard. The Northbridge controls a lot of your computers IO functions, even the PCI-E card socket, moving this to the chip will improve performance in the long run, but not yet. What I'm getting at is the early adopters of the i7 thought they could upgrade the processor more then once, they have quickly found out, they cannot, in true Intel fashion.