<< My Lite-On 16x dvd is very loud when spinning up. It is still quieter than my friend's Pioneer(can't remember his dvd speed...probably 6x).
When playing a dvd movie, after the initial reading, it's completely silent...I believe it reduces it's speed to 1x for playing just for this reason. >>
Same with my Lite-On. At full blast, you definetely hear it, though.
My Acer CD-RW is SILENT, whether reading or writing. But it has a fan that comes on sometimes when it gets too hot, and that is a little noisy.