My PC: P5E-WS, Q6600-G0@2.88GHz, Zalmans 9700NT, eVGA 8800GTS-512MB, Antec P182....

While idle:
In CoreTemp, the CPU core temp are 33, 34, 33, 33C
In PC Probe 2, the CPU temp is 25C and the MB temp is 35C.

There is a 10C difference in the CPU temp as reported by CoreTemp and PC Probe 2, is this right?

Yes.

Word, Playa.

at 2.8ghz
you should see 45c max at 100% output with a good cooler but the stock cooler maybe close
at 3.2 they climb to 55c and at 3.6ghz too 65-67c with a good cooler at 100% load

your temps are on the low side - its winter!