Since this is a current post...
I have the following card
http://www.amazon.com/MSI-R4850-2D512-OC-256-bit-CrossFire-Supported/dp/B001SIG5UM
However I'm looking at getting..
http://www.newegg.com/Product/Product.aspx?Item=N82E16814127435&Tpk=msi%20HD%204850
So I know I should be fine...