Guys, you are lucky I caught this thread. DO NOT GO FOR A PRESCOTT!!! I have made that mistake myself.
The service manual surely says it is supported but the machine misbehaves with it. You may be able to find some threads I started on the topic. Basically, the first time you cold boot a machine, it will go apes*t with the fans as the chip is truly hot. When you then reboot it, it will somehow trick itself into thinking the chip is actually not that hot. Either way, it is a ridiculously hot chip for our machines. You WILL have problems gaming (overheating -> graphics card downclocking itself). Oh and if you bug Sager, they will tell you that the chip is unsupported. Think about it - the power supply is rated at 120W, yet the Prescott itself eats up ~100W if I remember correctly.
I lasted a few months when I finally decided to bite the bullet, sell the chip at a loss and find a 3.2C on eBay. It will probably be even harder to find a 'C' series chip now (I got mine about half a year ago).
But if you can get one and compare, its heaven and hell. The 3.2C is only a few degrees warmer than the 2.4C I started with which does not amount to much fan noise.
Best of luck.