i second this, ATI drivers always crash. They are very unstable. That aside, if Nvidia made the drivers for ATI cards, Or even make ati drivers open source, we'de see a turn around. Nvidia is very good for stability but generally looses on the heat/voltage side.
I disagree entirely. It would seem to me that there's another problem at play causing this sort of problem, very possibly the PSU used, mother board, memory etc. In my experience there's little difference in the stability of nVidia vs ATI. ATI did have problem with their drivers but that was years ago (like pre 2000). Of course there have been 'bad versions' of drivers, but how many times have you seen "uh oh nvidia XX.XX drivers are broken, better roll back to YY.YY"?
In my experience the real difference comes down to personal preference. I have liked the image quality on my ATI cards, on the 2 nVidia cards I've always felt that they were a bit lack lustre. This is just personal but I remember going from the ATI 9800 pro to nVidia 7600GT and thinking "What!!???!?!". It wasn't just the short cuts nVidia were taking at the time with AA compared to ATI but what is to me the age old problem with nvidia: they can't seem to get a decent quality image from the card to my screen. Noticable not just in games but especially when watching movies.
This sort of judgement is VERY subjective, and isn't even the sort of thing you can even analyse by looking at screen shots produced by each of the cards.
Another problem is that benchmarks don't tell the whole story. It would be great if companies gave the full distribution of FPS within a benchmark, but they don't. All you get is an average and the min/max, if you're lucky. e.g. you might prefer a card that managed a steady 60ish fps but at a single point dropped to 20 fps in a game over one that had an average of 70fps but with frequently dipped as low as 24 ... but you won't get that information from a bench mark.
My advice is to try to get an experience of both cards first hand or, if you can't, watch the cards in action on video within a review with commentary and see which YOU prefer. I like ATI but I can see why others like nVidia ...