I've got both nvidia's surround and ati's eyefinity, I've found that a single 5870 is more than powerful enough to run 3 x 1680 x 1050 at max IQ on all current games. Nvidia's surround was equally easy to set up and use, but 2 gtx 480s (in my case) create so much noise and heat that i just have to give the nod to ati on this one.
I've also got 3d on surround with the gtx 480s, From my experience 2 x gtx 480 is BARELY enough to run 3 x 1680 x 1050 with 3d enabled. (close to max IQ) So if your planning on 3d in the future with your 275s get the 480s first... and a set of good active noise canceling headphones... and a personal air conditioner ;D
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vista 64 on these rigs
Q9450 @ 3.5Ghz | E8400 @ 4.2Ghz
8gb Muskin Redline. | 2gb Kingston Hyperx
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EVGA 780i FTW ----\--||___||--/---- EVGA 780i SLI
Antec TP Quatro 1000W \ :==^==: / Antec TP Quatro 850W.
Nvidia 9800 GX2 X 2 SLI \|--o--|/ Nvidia 8800 GTS X 2 SLI
1X 500GB Western Digital. \_____/ 3X 150GB WD RAPTOR RAID-0
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