According to these figures you need to OC the E8400 (3.3) to get Q6600 (2.4) gaming performance http://www.legionhardware.com/document.php?id=770&p=0
On lower end GPU's its a closer match between the 2 (both within 5fps on all games with both running stock speeds) which just shows we still have GPU bottleneck
Can you please link to the specific page which shows that? I just had a scan and didn't see a mention of the E8400. Also I think it's fair to say that in the vast majority of cases the E8400 does not need to be clocked almost a ghz higher to match the performance of a quad in games that aren't optimised for quad core.