I think we're talking about two things here - benching stable versus folding stable. Most of the people here in the WCG section are getting quad-cores because they can increase their production at a very reasonable price. The difference between crunching with a quad-core at 3.2GHz versus 3.4-3.5GHz is not really huge. Yes, you will get more daily points at the higher speeds. But is it enough to justify paying $1000 for a QX6850 versus $270 for a Q6600? For most folders, I doubt it.