I suspect that most of the other people on this forum will have better data than I, but even so, let me share with you what I did in your case.
My internal optical drive to my 2.0 GHz (macmini2,1) was gradually failing, and the next best thing to toast. I happened to have an old 5.25" bay external USB case lying around that I wasn't using, and went to the local MicroCenter store. (_NOT_ Best Buy!) Their sales person gave me two or three options. One of the options was to purchase either an Asian-OEM-Brand-name-I-can't-remember-that-started-with-an-"M", or to buy the Pioneer "DVD-RW DVR-K06" optical drive. I chose the Pioneer. These two drives apparently are the only ones that have the needed Firmware built into their circuitry so that they can work with a Mac.
For me, this has turned out to be the cheaper solution to replacing the internal drive, and it's probably faster, more durable, etc., etc., etc....
Your milage may vary.