According to the manual it supports up to a 433, but my guess is it will support a 533 (not a Celeron II, but the original PPGA Celeron 533) just fine.
It supports a 66/100 MHz bus, so with the multiplier locked you should have no trouble.
Coppermine support does NOT appear to be present (even though the chipset should support it), due to limitations on the voltage supplied.
Viper GTS