Is there such a simple answer to "which is better"? If not, which are better with AMD and which with Intel?
ATI make some good cards, but nVidia have the top end of the market with their 7800GTX, honestly if you're looking at a decent card then say your budget and then people might be able to find the best card for the price. As for what's better with AMD and what's better with Intel, i think they are both better with AMD, because AMD make the better CPU's...(correct me if i'm wrong someone)
AMD's processors tend to provide more bang for the buck than Intel, while being a proven solution in stability and performance. nVidia does have one up on ATi right now, so if you want the best performance, then nVidia's the way to go, and only because the 7800GTX is out. If it weren't for that, there'd be less of a gap in performance offerings.
It is really mostly personal preference. Unless you want to pay $400+ for a video card, they are about equal. The discrepancy is when you break it down and compare a specific ATI card to a specific nVidia card.
Its hard to say which is better without any specific models to compare. Top range cards out as of yet then its nVidia with the G70, but its a cat and mouse and it depends on whether ATi can deliver with the R520/R580. nVidia also have a very strong hold in the mid range area, with the 6600GTs very popular over the X600/X700.
