This is strictly my own personal opinion.
I've had a Q6600@3.5ghz on a DFI board for about a year now. I also have a Phenom 9850@3.0ghz on an Asus M3A79-T mobo. Contrary to what anyone tries to tell me, the Phenom rig just seems to run better/smoother. Maybe it's a placebo effect, maybe it isn't. I can only go by what my instinct is telling me. I use the 9850 as my daily rig while the Q6600 sits folding away in my basement now.