I plan to be building a i7 Core 920 soon and received a handful of "hand-me-down" graphics cards which I hope you can help me decide on which ones would be best for SketchUp use;

ATI Radeon 5850
ATI FireGL v8650
ATI FireGL v7600
ATI Radeon 4850

I think the 5850 is the newest of the bunch (but it primarily for gaming) whereas the FireGL is workstation class with 2Gb of memory, but it IS 2 years old (which is an eternity by computer time!). Which would be better to use? Would I benefit from "Cross-Fire" linking of them in SketchUp? Can I cross-fire link a Radeon with a FireGL?

I hope to build the new rig with 6Gb RAM and Windows 7 64bit - anything I should be aware of as it pertains to SketchUp?

Thanks,