my toshiba SD-M1612 is a pretty fast, quiet, reliable 16x/40x dvd-rom. Toshiba seems to have a good rep. when it comes to dvd-rom drives. They used to be (and still might be) the OEM supplier for dvd-rom drives for dell, probably because they were quiet and reliable.
Anyways, the last offering I have read about from toshiba is the M1712 16x/40x drive. It is supposed to be pretty good too, and it reads discs with safedisc protection if you are into that sort of thing. One thing though, the M1612 is a slouch at dvd-ripping, so if you plan on ripping dvds don't buy it (same with my pioneer 10x/40x). Lite-on dvds drives are very fast at ripping dvds and relatively loud in general.