i got a q9400 preddy close to your gen of chip. I get the same readings (lower tho cause im only OCing to 3.2 stock 2.66)
Mine get c0-34, c1-26, c2-37, c3-27 (idol)
room temp is around 22 degrees.
so i would say to you, your temps are A-OK
each core still has to run a thread even tho it reads at 0% at idol. that explains the temp differences.
the true test is when you decide to stress your rig and see what shes like fully loaded. Good Luck. remember Rock Solid Machine is better then Super fast but unstable machine.