Those are some great links Elf

Thanks. That was the information i was looking for!
Seems that the Celeron D is based on Prescott (0.09 micron) and the P4 is Northwood.(0.13)
The Celeron D does have SSE3 which the P4 do not, but is a tad hotter than the P4
I guess SSE3 isn't enough of a reason to use the Celeron?