Does this answer your question?
Screwed myself over
ATI & Nvidia have been making low, middle and high end cards for ages, and both have a "mature" unified driver that supports pretty well the entire range.
Good luck to anyone who can challenge them, but you'd have to be brave to try anything else unless you're talking about onboard lightweights such as the S3 bulit into VIA chipsets, or Intel Extremely average.
Anyone that isn't ATI or Nvidia needs to try 10 times harder, and it sounds like XGI are falling well short on getting decent drivers out.