Claire, I'm using a 5163D with my 700 mHz flat panel iMac. I connect via a Firewire cable and it works beautifully, so long as you're using Toast for burning.
There is a utility called Patchburn that in theory allows the drive to burn direct from iMovie, the Finder, etc. In my experience it can't handle hardware specific features like buffer underrun etc. properly. I wish Apple would give it system-level support, but so long as you plan to use Toast it won't be an issue.