a socket 370 P3 m-board supports a P3(Coppermine) from 500MHz to 1.0 GHz and a P3-Celeron from 533MHz to 1.1GHz. The board should have the model number printed on it close to an edge, or sometimes between the slots.
Info from this site:
http://www.geek.com/procspec/procspec.htm
If the m/b also supports a Tualatin P3, it'll take up to a 1.2GHz P3 or a 1.4GHz Celeron.