It´s a nice game! But, andr3_0 you are right, it's old!
I've tried disabling the 6520g but it gave me an error on Catalyst, probably because the LCD is connected directly to the APU and the other GPU acts only as a helper!
The solution is in the hands of AMD, to create a driver that allows the use of both Graphic Cards no matter of the Directx, a normal Crossfire platform...a driver that make use of CAPS, because there is an amd profile for Starcraf2 Crossfire on CAPS if I'm not mistaken!
Thanks for the help