Quality and speed
Frantisek, HardOCP has done a bit of a demolition job on the 2900XT partly with regard to the different AA filters including the different tents.
They have included a number of screengrabs to illustrate the quality of AMD versus Nvidia and frankly they are pretty much identical in most respects however when it comes to AA the AMD card images look blurred. I have no intention of taking issue with HardOCP - in the main they do excellent work - however I have been in this situation way back in the days of Radeon 9800.
This was a time when AA was quite novel and I simply wanted to illustrate what it could do so. I used Microsoft Train Simulator as an example because the train tracks suffer from horrible jaggies as they converge towards the horizon. Enabling AA smoothed the image considerably so I set about taking screen grabs to illustrate the success.
In the images the rails looked good with AA but the trees that line the track looked like green lollipops with no distinguishing features and the grabs with AA therefore looked terrible. Much like the images on HardOCP..
Of course I was looking at stills from a moving image and was effectively missing the point. As you drive past a tree you can't see the leaves and branches. Stand under a tree in Oblivion and you get the benefit of all sorts of eye candy.
Ever since I have been very wary of taking screen grabs as they often show visual information that is out of context.
As for the most recent comment, yes it would have been 'fair' to run a pair of Ultras in SLI however I only had one Ultra - does anyone have two? - and simply wanted to illustrate how £500 of AMD hardware compared with £500 of Nvidia hardware.