Replacing Desktop P4 with Mobile P4-M

[davidn]

I've got a Clevo 5800P notebook which was supplied with a desktop P4 CPU (478 pin PPGA FC-PGA2 package.) The motherboard and CPU died due to overheating (pins in the socket burnt out!) and I now have a replacement. The motherboard has a 845MP hub (a mobility chip) and a Radeon mobility 7500 GPU, but the manufacturer says that the CPU must be a desktop unit. Why would that be? I'm keen to use a Mobility P4-M CPU if I can, because that's what the 845MP was designed for. Is the manufacturer right? Am I doomed to a desktop CPU? What are my options?