You've got the best card w/ ADC incorporated.
well, there are only 2 current manufacturers, Nvidia and ATI....
ATI's 9800 is the only retail card that would outperform the GF4Ti...the only drawbacks of the 9800 are that it doesn't support hardware graphics acceleration in 9...it will work, you can boot, but processes which would typically be handled by graphics card are done by the cpu....so, if you treasure any old games that don't play well in classic (i've not gamed in classic...) then you should stick with what you've got.
the other offereings from ATI are the 8500 and 9000, neither hold a candle to the GF4Ti at higher resolutions/workloads...
You could get an adapter for the 9800 if cash is burning a whole in your pocket...
consider 2 things: even if a 9800 is a better card, depending on the machine you want to put it in, it may not make much difference....if it's not AGP 4x slot, fuhgetaboutit...
if you don't have a totally crankin' fast cpu to feed it, fuhgetaboutit....it will starve there, just using more energy, putting off more heat, and wasting cash better spent on other things...
I think the presecnce of the ADC, and the compliance w/ 9 make the GF4Ti a prize on the ebay/used markets....you may well get a good price for it should you sell...
OOhhhh....I forget where, but remember ATI is to possibly bring out another low-end card to replace the 9000...but with the generation change, this may be what you're looking for...will be consumer priced, but it's anyone's guess what the port config and pricing may be....
good luck