You would be surprised at the number of gamers who have to use their PCs for work as well. In that case, Ati gamer cards are great for games, but pretty much games only. You would have to buy a FireGL otherwise which are very expensive and not as good at games.
I've worked at a number of studios who use Nvidia gaming cards in their productions. It saves money from having to buy a Quatro or FireGL, and you can play games on your lunch breaks.
You do realise you can softmod most Ati cards to their FirePro equivalent with a 3x increase in performance, AND that FirePro cards are pretty equivalent to their Nvidia competitors.
Can't wait for a softmod for the 5870 to a V8800 (which is 40% faster than the old V8750)