Since this is all i’ve thought about the last week or so i’ll give my conclusions. For better or worse ATI has so many mid-range quality products and they’re much better poised at the 200$ segment.
The 6600 GT is a good card, as i have it, and it has all the cool shaders 3.0 and HDR lighting. It is however only slightly faster than the 9800 pro (it’s about equal or slightly better than the 9800 XT). It’s gotten really pretty cheap as well, as least online.
NVidia AGP cards are getting scarce and i think they have stopped or are slowing down production of NVidia AGP … anything. This has kept AGP card prices artificially high in some cases. The 6800 GT is probably the most solid last gen card out there, but it’s still almost impossible to find one less than 300$.
Personally if you can get the 7800 GT for 350$ there is really no reason to settle for less, if the less is only ~100$ in savings. Really nothing else in the 6xxx family is worth bothering with. The Ultra remains far too costly, the 6200’s are pointless for gamers except someone wanting to run Counterstrike at 800x600 with no AA on the cheap.
There used to be something called the 6800 NU that you could supposedly overclock to the GT, but it seems to have dissapeared. It was supposedly the price of the 6800 with the potential performance of the 6800 GT.
Actually you might consider the 6800 vanilla; it can be faster than the X800 pro, although it’s probably about the same speed generally.
There is the ATI X800 GTO2, but its virtually vanished because of it’s popularity. When (if) back in stock it should sell around 199+$. When flashed with a new bios they become apparently X850 XTs, which is really not a bad deal. Of course, no shader 3.0 or HDR lighting.
Of course the problem is that both the GTO2 and 7800 are PCI-e only. There was a rumor of a GTO2 AGP but it is apparently false and there are no plans to bring that card to AGP.
Personally i think ATI cards have far better 2d performance, if that possibly means anything. I remember there were tests comparing signal quality and NVidia cards tested to have more noise and interference because of poorer quality resisters (or something). But whether ATI cards, most or all of which are made in China today, still perform as well in this regard, i just don’t know. And they’re about to kill what little warranty they had on new ATI branded cards.
There is another cheaper ATI option; the ATI Refurb Clearance Center. Right now you can get the X800pro w/ 3 year warranty for 179$. I haven’t checked shipping and taxes, but that’s not a bad deal. In some games and resolutions, the x800 is only about 30-50% faster, with 4xAA it can be more than double. It’s probably 10-25% slower than the XL, depending on the game.