Aero 7+ looks a very good option. As far as I can see from a quick look at reviews, it will do the job.
For the temperature, I will let you know in 1-week time (I have to build a temperature monitoring device). For the moment, I have no idea because I have no sensor attached to the CPU and personally; I don't trust the bios values. However I think is below 50 C because the air coming out of the heat sink isn't even worm. Usually my rule is that if you can't keep your hand for 1 minute on the heat sink (because is too hot) than the temperature is above 60 C. (the fan is rinning at full speed)
I read somewhere that P4's slow themselves down to prevent overheating.
I don't know about P4, but I never heard of such feature on AMD stuff. (maybe is true for laptop thing)