All these votes for the 3700+ when they are the same clock speed but the 3500+ is ~$60 cheaper?
I know I've said it a lot, but I've got a 3200+ Vience and a 3700+ SD and when clocked to the same speed, I don't notice a difference at all in anything. The highest OC is the same for both, so there is no advantage there. Personally I'd skip both the 3500+ and the 3700+ and go with the 3200. It has the 10x mulitplier which is more usefull to me than the 11x on those other two and is much cheaper.
Also the E6 revisions are supposed to be great overclockers and those are only in the Vience flavors...