Well, the Crome Orb works just fine for my Duron 600@950, which is what I am typing on now. Doesn't even get warm to the touch. And, yes, there is plenty of heat transfer going on, cause the chip is not hot, either.
Also, it gets my T-bird 700 to 850, same results. For some reason. the T-Bird 700 poops out at 900 on both of my Motherboards (A7V and KT7). I don't think its a heat thing tho, cause it won't even post at 900.
Any how, there are better solutions for air cooling than the ThermalTake products, but I can get Orbs locally and cheap, so I use them. If you are going to have to order, I would have to agree with Jeff, the PEP 66 seems to get rockin reviews.
Crank it up!