I got a 3.0GHz Prescott, and my idle temps are in the 39-44º range. Give the AS5 time to burn in and see if it helps. The last few days the temp. has been decreasing a couple degrees a day (it started at 48-50º)
FYI, I tried to get a Northwood, but those little bastards where $50 more and really hard to come across with. I ended up buying this Prescott and a Zalman 7000B Al-Cu+AS5. So far so good.