For a lot of applications, the X2 cards or SLI/Crossfire mode is a huge boost.
Unfortunately, wow is not one of these.

A 5870 is definitely on my "want" list.
Unless the GT300 comes out soon and is better.
Could care less about the DX11 stuff, basically I play wow and some older games.
Although I'll try Starcraft 2 and Diablo 3, I'm sure.