Hard drives do not contain steppers as far as I know. Floppy disk drives. CD/DVD drives don't normally do they, the one for the drive is a normal motor with sensors for open/closed. The one for the laser has sensors each end and a screw drive which is accurate enough to just use a controlled normal one (or is it a tiny stepper). I think it is the same in floppy drives.
There are 100% definitely stepper motors used in 5 1/4" floppy disk drives.....I have about 5 on my desk right now. and Iv got steppers from old pre 386 computer hard drives.
And here is a video about CD-ROM Drive Stepper motor hacks as they are used to control the trays http://www.youtube.com/watch?v=dSKac6EPkrc