ATI's problem isn't the drivers with their mature products, its the driver installation/uninstallation. AIW cards (and the rest of the Radeon line) are very stable with mature drivers and a feature laden multimedia suite that no other card/chip maker matches...
but,
The driver installation program/procedure is horrible. Its non-intuitive and there is no clear-cut uninstall procedure that a nOOb can figure out. I've never been more than a driver re-install away from a fully functioning AIW card in over 2 years myself.....period, but thats because I mastered clearing my registry, manually installing drivers/WDM's, MMC....on and on long, long ago. I don't have problems, but I can see why many have. If ATI would keep their registry entries and naming conventions in the same spot in successive driver releases, maybe someone could create a decent uninstall utility. Then have an installation that checks your rig for the proper components for the various cards features...man that would be sweet!