@ peoy - the Apple Matsushita/Panasonic UJ-85JC A Super Drive DVD±RW-DL-CD-RW is a great alternative for the ealier MacMini drives as they also have an IDE/PATA connector, so you just need to swap over the membrane/ribbon connector and you're good-to-go !

They were usually fitted in the earlier MacBooks, but I won't tell anyone if you need to fit one in a G4 MacMini.

There are plenty of them still about, for fairly little money, in the usual online buying/selling websites.

You can't use the Dual-Layer (DL) capability of the drive with MorphOS as it's not supported, but you can use it on your device if you use the Mac Mini to Dual Boot (which it sounds like you do) to Mac OSX, as the Dual-Layer technology is supported on Mac-OSX, at least it is with the Toast software, though there may be other alternatives.