That's because you always prefer Nvidia.
either 3870's or 9600 GT's are a good choice. 9600 GT's perform a bit better when you've got anti-aliasing, 3870's perform better without it.
Crossfire is extremely easy to get running. You literally just have to check one box.
The 9600 GT's have single slot coolers, while 3870's have dual slot coolers.
The 3870's will run cooler, and won't be as loud, though depending on your motherboard, they might prevent you from using PCI-PCI-E slots you might need.
Unless you get aftermarket cooling (such as the Thermalright HR-03 GT's, which fit on 9600 GT's and
I'm pretty sure Catalyst 8.5 performs significantly better overall than Catalyst 8.2
the newer forceware drivers also have performance improvements, but not as much....