This link will give you and idea of what each chip runs at different benchmarks. The Prescott actualy runs hotter than the Northwood. From my experience, the Northwood does not overly run hot, I use one system fan and keeps things from over heating. This was reduced from three fans, as I had a voltage problem on the 5.5 rail while running a ATI 9700 Pro, leading to system crash. Once the volatage problem was cured, all runs fine, and well with in temp ranges.
The Northwood does run hot, as compared to its AMD rivals, a first for once, as the AMD's were always known to run hotter than Pentium's. Read the results in its entirity, and perhaps will give a good comparison of several chips in the range you are looking for.
http://www.hardcoreware.net/reviews/review-195-1.htm