I have an iBook G3, 700, 640 ram and use a Sony DVD RW U18A via firewire and use Toast 6 Titanium. Works great. 8X for dvd, 40 for cd, have burned both. OS X picks it up and Toast just works. By the way, I have the burner daisy-chained through an external firewire hard drive. Oh, and I'm using 10.2.8.
No problems, just easy to use.
Henry