<< Well , it`s all in the Clock, especialy when the difference is 650Mhz >>
Not really: a P3 1.2 GHz (tualatin) is much cooler than a P3 1.0 GHz (coppermine), for example.
But to answer your question Spankthru, yes T-birds run hotter than Durons. T-birds are, I belive, the hottest chips out there. Athlon XP's are a bit cooler, P4's are quite a bit cooler, and P3 tualatins aren't even in the same heat league! Having a T-bird run stock @ 40-50+ deg C is normal. A 10C temp diff should be nothing to worry about.