just to correct you on the math, 9800 pro is only 10-15% faster than 9700 pro. This is true in general, and in particular in doom 3. And the only reason it's faster is because the core and memory clocks are higher, by 17% and 10% respecitively. That fact has been established and known ever since the 9800 pro was released. So despite what ati says, apart for some minor changes, it's 99% the exact same core used in 9700 pro and 9800 pro. So the difference is as I said between 10-15% (and never more than that), and that doesn't change with or without AA/AF.
I still like the 9700 pro, it can run almost any game on med-high @1024x768, including the new engines of doom-3 and far cry, which will be the basis for many games in the next two years. So if you're happy with this kind of gaming performance (which is quite good, but not state of the art), the 9700 pro is a your card. Also 9700 pro has a claim on last generation's cards big leap in performance as it was the first to be released, thus earning a legendary reputation as a breakthru product (just read the rave reviews from the end of 2002). long live 9700 pro!