Curiouser and curiouser. I've just updated the Catalyst drivers from version 11.5 to 11.6, and 'Windows Experience Index' claims to have detected 'new hardware'! So I tested again, and lo and behold - the graphics scores go from 6.4 to 7.9!
Evidently, it doesn't measure hardware at all...
You shouldnt be at 6.4 with that GFX card mate...even with this inferior benchmark.. everyone here thats used it with 69## gfx cards gets 7.9