I've had both a 9700 and a 9800. The 9700 was a problem little bastard. Would only work on some motherboards so I scrapped it for the 9800. I liked it but I hate having to use ATi's software for stuff. Here recently I upgraded from the 9800 (well more of a swap not an upgrade) for an nvidia card and I do like their setup a lot more. Seems to be on par with the 9800 as far as graphics go and more user friendly.
Im a big ATI fan... but since switching to linux.. the ATI drivers aren't very up to par compared to windows. I just ordered an older GeForce Card... I wont to see how it runs under linux if this card works well (considering the age).. ill be turning into an nvidia fan. If not.. I will stick with ATI.
if you want to save some $$$ but still get a high end card, either 9800xt or nvidia 5900 ,I would go with the 128mb versions...There is not a single game on the market that needs 256mb of video ram, and by the time there are games out that would benefit from the extra memory, the card is going to be out of date and it will be time for an upgrade...Just my $.02
I run a radeon 9700pro now after using nvidia, and I love it. I bought that card off ebay for $180 about two months ago. I had some driver issues at first but after downloading the latest ones it has been great...awesome fps with UT2003 benchmark...