The *only* reason I've been buying NV cards lately is for Folding @ Home. Between my overclocked 285 (702/1584/2754) and 275 (648/1440/2304 - factory OC, I plan on OCing further) I get somewhere between 17,000-19,000 points per day. If ATi's cards could produce the same amount of points per day as Nvidia's, I would buy them instead. It's pretty sad when my roommate's beastly 4870x2 gets outperformed by my old 8800 GT which I'm passing on to a friend. If and when Pande Group ever gets around to releasing the GPU client version 3 written in OpenCL, ATi cards should finally start performing closer to their NV counterparts at which point I can look at replacing my 285, 275, and 8800 GTS 512 in my 3 gaming PCs. Hopefully by that time Northern Islands will be out and I can upgrade to DX11.
I still have something of a soft spot for AMD & ATi parts. I used to be something of an outspoken FanATic over at Rage3d but have moderated my views quite a bit since G80 and Conroe came out in '06. Sadly, I haven't owned an ATi card nor an AMD processor since the release of the aforementioned architectures. Holding out hope for Bulldozer and Northern Islands though.
For gaming purposes its all a wash right now as the games I play aren't that demanding (Titan Quest, UT3, COD4, L4D) and 3 monitors I use are a 1360x768 32" LCD powered by an 8800 GTS 512, a 1680x1050 22" LCD powered by the GTX 275, and a 1920x1080 42" plasma powered by the GTX 285. If I were running multiple displays or higher resolutions I could see the need for more horsepower for gaming.