Apple today posted a firmware update for the 550MHz and 667MHz PowerBooks, bringing the firmware on these models to version 4.2.9.
The firmware update includes improvements to FireWire target disk mode when running Mac OS X, improves startup on systems with 1GB RAM and enables Netbooting over gigabit Ethernet, according to information provided by Apple.
If you are using Mac OS X, you must restart your computer in an OS 9.1 writable partition (not CD or network disk) and then begin the update.
Firmware update 4.2.9 is available from Apple’s Web site.