I've pretty much given up here but what they hey I'm in the mood to post.
ATI's drivers are not unstable. The issue isn't with the drivers, this thing is a bigger issue with Window's WDM driver model in general. The same thing happens to nvidia cards and statistically it happens more often with them for some reason. My work laptop has Nvidia 335M graphics and it has that very problem with the .dll not responding. No known fix. you deal with it. My desktop suffers form it occasionally. Again you deal with it.
I dunno why you are listing eyefinity as a bad thing. It;s a great thing if you have a bunch of monitors you aren't using. It's spelled CUDA btw, and you will most likely never use it. I have actually used it in an academic research environment and let me be the first to say it's crap. ATI's environment isn't great either and GPGPU is far from being as mature as everyone wants you to think. Right now it's where Java was in the 90's. ATI's newest cards have DX11, and had them first. Physx is about as useful as Cuda, the only game where it is noticeable is mirror's edge and I don't think anyone plays that anymore. And 3d visuals has everything to do with the game and monitor compatibility first and foremost. If you don't have that and that's a massive earth crushing if then it's useless.
The only points that matter with a video card, and I will say this to the end of days, are price, performance, heat reliability, and price/performance. The gimmicks are just that. I've been doing this for a decade now and there has always been gimmicks, very few of them ever become legit. SLI/Crossfire was one of the lucky ones. And it took 3 generations to mature to being relevant to most people.
The GTX480 is very hot and very heavy on power usage. The GTX480 is running at 94 degrees Celsius under load, that's over 200 degrees Fahrenheit! You could almost boil water on this thing. It also eats 300 watts under load. that's a big chunk of your power budget. I sure hope you have a 600+ watt psu handy. It's also as loud as 2 GTX285s, Headphones required. It's also worth noting that AMD refreshes their line every 6 months with a die shrink and clock speed increase. That isn't too far away at this point. They may very well release a faster card. And the ATI cards are cheaper. The GTX480 is on average 25-30% more expensive (in America) than the HD5870. It's only 10-15% faster. You should take all of this into account.