That's not a huge improvement, at least at stock . That said, a decet overclock on a 6600 (3.2ghz or so) should be  decently faster than my opteron170  @2.8    
     
They screwed up the review though, LOCKON is STILL NOT GPU BOUND @ 1600x1200 as long as you have a semi-decent GPU.   
I get the same framerates @ 1600x1200 with AA and AF on, as I do with them off, also, changing the resolution has almost NO impact, thus it's NOT GPU bound, but CPU BOUND.   
PS: I wish they had higher resolutions for the test, as 1600x1200 is kinda low these days (for what GPU's are capable today)