Only the P2B rev 1.12 has official support for Coppermine Celeron processors.
Older revisions of the P2B can be made to work with the Celeron2s.
Revisions prior to 1.12 do not support the 1.50 volts requested by the Celerons.
To make the Celerons work, you need the latest BIOS update, and to use a Slotket. You need to set the voltage on the slotket to 1.80 volts, which is the minimum all P2B boards support.