Arschloch is right. What someone is getting as a temperature reading from their Asus board, let's say, may indeed be quite different from the reading someone is getting from their MSI board. Some boards read the temperatures a little bit high, some boards read the temperatures a little bit low, and some board read the temperature just right. I have a 1.8A@2.52 GHz that idles at 50C and goes to around 67C under a full load. This is on an MSI 845 Ultra-ARU motherboard. At first I thought this was too high, but then I talked to some other people who have the same motherboard, and the majority of them had high temperatures just like I did. Also, I dug into Intel's datasheet for the Northwood processors and found out that even if my temperatures were 100% correct, I'd still be within Intel's specs for temperature. (Take a look at the P4 Thermal Solution thread I started. A lot of interesting information about the Northwood chips in there, as well as a link to the datasheet.)
So unless you're getting temperature in the mid seventies under full load, don't worry about your CPU being too hot.