Final system requirements have been set for QUAKE 4 for Macintosh, expected to ship in March.

QUAKE 4 System Requirements:

Operating System: Mac OS X 10.3.9 or later
CPU Processor: PowerPC G4/G5 or Intel chipset
CPU Speed: 1.67 GHz or faster
Memory: 512 MB or higher
Hard Disk Space: 3 GB free disk space
Video Card (ATI): Radeon 9600 or better*
Video Card (NVidia): GeForce 6600 or better*
Video Memory (VRam): 64 MB or higher
Media Required: DVD Drive
Multiplayer: Internet (TCP/IP) and LAN (TCP/IP) play supported. Internet
play requires broadband connection.