Actually, the newer Pentium Dual Cores are basically Core 2's that are at a lower clock speed and bus speed. They're quite OK processors. My advice is to just avoid Celerons like the plague. 😀 (Though the newer dual core Celerys probably aren't terrible...)
EDIT: Well, technically you ARE right - the PDC is a Penryn-based chip, right? So that's older technology... 😉