Great review, though the Quake 4 frame rates still seem rather precariously low when it comes to every graphics card tested and shown.
Another thing in question - a $40 price for the 8600 GTS seems a tad low, even if it's not quite a midrange card anymore - shouldn't it be anyplace closer to around $80? Speaking of the 8600 GTS, I'm also rather shocked that the 512MB one seems to be slower than the 256MB one for the most part. That's a Biostar one if I'm not mistaken, but some of the reviews I've seen of other 512MB ones (the Gainward one on Fudzilla an the Vvikoo one on Hartware.de) have it getting significantly higher frame rates (a 20%-45% augmentation) when FSAA is enabled at higher resolutions. I myself have a Gainward one, and am getting 37FPS average in F.E.A.R. at 1600x1200 w/4x FSAA & 16x AF instead of 30FPS (running it at stock speeds, with no texture filtering optimizations enabled, though even with them on I still get 37FPS running the built-in test at the aforementioned settings). Not to vaunt or anything along that nature.
And just to add, I think the GeForce 7900 GTX's score in 3DMark03 is quite high; it is not significantly afar from the 30,000 mark, when if my recollection serves me correctly that card used to get around 24,000 at the most at stock speeds (not in SLI, of course). It must be that it's been paired with a good CPU and that nVidia had ameliorated upon their drivers quite a bit.
Also, SP3 isn't installed on the test machine? If I may ask.
And whilst the 9800 GTX may not be all that challenging to the 8800 GTX, consider how many times more expensive the 8800 GTX was, say, a year ago? So a $280 price tag is rather nice, keeping that thought at view. I wouldn't mind coming to grips with a board that's slightly slower at that price.
Nevertheless, good review.