I also recommend the xlr8yourmac database. After reading the posts there I decided upon a Lite On combo drive. Now there are two versions that work (that I know of). I forgot the model numbers but you can look them up at xlr8yourmac.com. I spent a long time looking for the older drive because it works without any driver hacks. According to others, the newer one works too but you might need to run an enabling hack (also available from xlr8) to get all the burning functions.
The Lite On drives fit fine, although I never bothered to fit the pismo bevel on.