Also found this
gregsmithcts - Oct 18, 2011 - 08:21 PM
Post subject: RE: Difference between ATmega328, 328P and 328PU I think you'll find the differences are just in the silicon and affect the power consumption. In terms for functionality and pin compatibility (and programming) there is no difference.
So my problem is solved.In duemilanove I use the atmega328P and in my custom board I use atmega328 XD