Around room temperature + 20 degrees Celsius.
Right now, in Internet and not doing video, my i7 930 is at 92F (I do not overclock) with a Cooler Master N520 CPU cooler
Ideal would be 29C to 36C. Average would be 36 C to 45C. Less than average would be 47C to 53C. 53C to 65C would really be pushing it and anything over that would be to hot for idle since load will add 20C to 30C to the idle temps.
My temps were running high, I cleaned my air filters and they came down to normal