Showing how quickly graphics cards are being introduced, ExtremeTech has an in depth analysis of Nvidia versus ATI graphics cards. For their test they used the ATI Radeon X1800 XT, and for Nvidia they used the GeForce 7800 GTX. Of course, ATI just released their X1900 line of cards, so the information does not address their newest offering.
The comparison is still a good test of the two different vendors approaches to increasing the speed and capabilities of their cards. In the end, they do choose a winner. However, they rightly point out that this may be entirely dependent on what applications you use it for, and how much work you are willing to put into optimizing the software to run it. Check out the ExtremeTech link to read their very detailed comparison of the two products.
Posted by Jeff