|What jam said, but in short, the Pentium D is usually a dual core Pentium 4 cpu (Net burst arc.). Celerons used the Pentium 4 core's with half the cache missing up until the later celerons which switched to the "Core/Core2" core.|
Every intel CPU today(excluding atom) uses the "Core" cores. The pentium and celeron names, are just rebranded Core cpu's with less cache, or single cores. The i series (i7, i5, i3, etc) are Core based CPU's with the memory controller on-board the cpu die itself.
The Core2 is basically a Core1 cpu with improvements, the Core1 is a pentiumM with little change, the pentiumM is really just a Pentium III core with improvements, the Pentium III core is nothing more than the Pentium II with SSE, the Pentium II is nothing more than the Pentium Pro with inline cache, and the pentium pro is the pentium pro.
There have been no "new" cpu designs to come from intel since the Netburst arc. and the itanium arc. Both are now defunct. All modern intel cpu's are nothing more than old cores with process shrinks, added instructions, vector units, etc.
PowerMac 9600(1 ghz G4)
ATi 9200 PCI