Actually, I'd recommend just buying an HD 6670 DDR3. That thing plays fine with my 965 X4. I get 40-50 frames consistently @ 1280X1024 with Skyrim (Though it's more at 40, It's silky smooth. Almost never get drops, even with massive-scale battles, E.G, 15 whiterun guards against 45 bandits).
But if you want even more grunt (Because you want to do SLI), I'd even recommend getting a 6850 for £85 at ebuyer.
Anyway, back to OP.
I don't think that they will SLI well, but don't take my word for it. I've stayed away from NVidia after my 8600GT. Never liked their power-draw.