Grabbed a NEC 3540 during a deal on newegg's, like under $40 shipped or something. Have burned 50 dvd's with it, and haven't heard it once. I've got a quiet case with only three fans in it [cpu, gpu, and exhaust fan]. It's got a bit of following behind it that likes to make firmware for it, so it helps me play my +r's on my older dvd players. It seems a lot of people don't like it because it only utilizes one light on the faceplate, a green LED that is on when the disc is being read and the same green when a disc is burning. Personally, I already know if I'm reading the disc/burning a disc because I initiated such an action.
I suggest internal but I am biased; I had a CD burned off of an external burner and it was jumping around on the cd, a wierd problem I never saw with any of my internal drives.