The maximum temperature stated by Intel for the E6600 is 60.1 degrees celsius. So, any temperature beyond this limit should be considered as negative for the E6600. I never overclock my hardware and I also do not use power management schemes to do downclocks. Everything runs at stock speeds and as I said above, my CPU remains pretty constant around 30 degrees celsius at idle and the maximum it ever reached was 40 degrees celsius during a heavy gaming session.
What I can advise you if you are experiencing high temperatures is to check whether you have securely placed your cooler on the CPU (as described in your cooler's manual) and also to check whether you don't have some wires blocking the air flow around your CPU area. Moreover, make sure that you well define your fan settings in the monitoring software of your motherboard.
Let us say you have a cooler with 3000 RPM maximum. So, you can put the settings like this:
Minimum fan limit = 20% at 20 degrees celsius
Maximum fan limit = 100% at 50 degrees celsius
In fact, these are my own settings and I am pretty satisfied with the cooling results.