The older black Apple remotes are compatible with all of the 63x, 6xxx and 5xxx machines. In my experience, the remote can be used to change channels with a TV tuner, control speaker volume, toggle between Apple Video Player and Finder and control CDs (skip, pause etc). Of course, you can also use the remote to power on and shut down compatible Macs which is very cool!

There may be other functions which I have forgotten about, it has been a while since I've played around with my remote and 5400.