Personally I wouldnt want my 45nm chip to be running over 60-62 degrees under prime95 after 10mins.
Idle temps between 25 and 35 are fine and depend on your cooler.
As Haserath stated the redline for your chip is 70 degrees.
Saying this if your running at stock clocks the wolfdales shouldnt go over 60 regardless. If this is the case you need to look at loss of efficiency, cooler blockage, room ambient temp yada yada.
Prime is a great test, you will never generate the sort of heat in day to day applications as you will running this program, so if your testing and hitting low 60's, this is your worst case temp your system will hit no matter what you do with it.