[PDupre]

Felix,

Seek and ye shall find. From compatibility section of site:

Note: The following new models are currently not supported with Pro Tools III:

466MHz PowerPC G4 533MHz PowerPC G4 Dual 533MHz PowerPC G4
667MHz PowerPC G4 733MHz PowerPC G4

Additional Requirements:

Mac OS 9.0, 9.0.2 or 9.0.4 required (Mac OS 9.1 has not been tested with Pro Tools III)