Yeah, but the only way you're able to upgrade to an 8 series card is if you purchase a new laptop or motherboard. For a relatively cheap upgrade to some not too demanding games, go for a 7900 GS or GTX.
I always thought that two mid-range cards in SLI would out-perform a single high-end GPU? I mean, physically you've got twice as many cores etc, surely if you overclocked it to the same speeds as the high-end card it would perform significantly better?
Its got to be the graphics card, I mean if it works without it then the problem evidently lies within the graphics card. Try downloading the Dell Diagnostics Utility from their site, and diagnosing your GPU card with it, should say where the problem lies.
Yeah, sounds like your GPU might be heading for the door. Mine had the same sort of errors, a lot of BSOD saying stuck in an infinite loop, due to nv4_disp.dll. Might need to start looking at a replacement, that 7800 runs really hot which could have helped damage it.
Another thing, you need to make sure that your driver for your 7900GS Go is AT LEAST 84.69, otherwise the card will have some issues displaying the screen through S-Video (the screen was squashed and distorted with earlier drivers). mine works perfectly, make sure everything is connected up as it should be. It might have something to do with your TV, try all the different AV channels on the TV too.
Yeah, I would recommend getting the 1920x1080 screen, it will play BluRay films back perfectly, pixel for pixel. Mind you, on a 17" screen you will be hard pressed to notice a significant diference, but if you're anything like I am you will definitely appreciate the extra clarity and sharpness.