Does the P4C800 support the Prescot chip you have installed? It sounds like it is misinterpreting the CPU data. If the FSB is running at the rated speed (800Mhz), then you can be sure that your CPU is actually running at 3.2Ghz and the MB is only misreporting the speed based on a wrong FSB multplier interpretation. Now, if your FSB is NOT running at 800Mhz, that is a bigger problem.
I do not know anything about the P4C800 (I have the P4P800 Deluxe myself), so I do not know how well it handles Prescot processors