While I admit that ATI has had several issues with drivers in the past, recently they have been stellar. When the 9700 came out the drivers were fine, they were even good with the demo boards they sent to reveiwers.
As for GPU power, ATI has taken the lead in GPU performance, in most benchmarks, the GeForceFX only barely beats the 9700 pro and the Geforce runs at 400 - 500 mhz, whereas the 9700 runs in the 300s somewhere, don't have exact numbers on me.
ATI is about to release another card, code R350, the 9700 was R300. It will have a clock rate closer to the GeForce and so it will probably beat it. So Nvidia will be playing catch up again.
If you want a new card, I'd wait a few months, prices should fall somewhat by spring.
I'd be willing to bet that's why they aren't going to push out the FX very much.
All that said. AH is more CPU than GPU so you will be much better off upping your CPU and/or MB & RAM buss speed.
Personally I have a Radeon 8500 and a Duron 1100 and I have no problems anywhere.