bugs suck
Seem to have found a bug in the p4-clockmod CPU Frequency Scaling-driver: it doesn't allow you to select the highest possible rate the processor is able to run. Which pretty much puts me back at having a 2.0Ghz P4M instead of a 2.2 one.
Trying to remove the module and replace it by the ACPI driver didn't work either; modprobe segfaulted. Grmbl.