They released a pre-release concerning 98 support. They only list the WHQL drivers on the WEB site right now, but they stated they will have support for 98.
All drivers released after 7/31/2002 will not longer be able to get WHQL from MS, as they are dropping the program for 98.
You may want to visit the Rage3D BBS, as ATI reps post information there regularly.
As far as you computer goes....you just about need a 2+Ghz CPU to keep the card busy enough, but ATI looks like they are going to have 3 different versions of the R300 family. The PRO, LE, and normal versions all running at different clock rates and at different price points.
The LE version appears to be clocked to compete head to head with the NVidia Ti4600, but be cheaper.
This is all speculation right now, but it does make sense. ATI needs too fill the big price gap they are going to have between the 9700 ($360.00 U.S.) and 9000Pro ($130.00 U.S.).
In the workstation market, a picture of a quad R300 board is making its rounds. Rumored to be able to do real-time photo-realistic art and be part of the FireGL line. I beleive this product will not make it to production, simply due to the fact you would need a dedicated power supply to run it, as it would require about 200W to power just the card, but you never know.
I see ATI having a problem with the 9700. It is going to take one screaming CPU to push the card and, and at least a 4X AGP bus. I can see guys buying it and putting it in a 1GHz/AGP 2X system and complaining about the lack of performance. ATI would do well to state a CPU speed that would push the card, or at least keep it busy.