Uhmmm..... regarding the idle power, its fine to turn speedstep C1E and all that crap on. I posted a thread about this, and it was almost unanimous that I should turn it on.
Idle frequencies may be higher than before which is why many BIOSes now use an offset voltage from "normal" voltage. Find out what it takes to run at 4.5ghz or whatever, say 1.3V, and if your normal voltage is 1.25V, just run at Normal +0.05V. Thus, it will scale your processor like normal, but add a 0.05V offset.
There's no point in wasting power in running at a full 4.5 GHz 24/7. It might not make the most difference, but for my i7 930, it saves me 20-30 W by letting it ramp down and have the VCore drop.
Honestly, dropping your VCore isn't gonna drop the power that much. It's enabling C1E and C3 and C6 states that will.