I was wondering. Is it possible to replace my imac's (see below) cd drive with a superdrive? and if yes, does apple sell superdrives separately?
As mentioned above, you can get a replacement that'll go in the place of your current drive, orrrr.... you can get an external dvd writer. Cheap and a whole lot faster than a slot loading (vertically mounted no less) drive will ever be.
If you want a simple, no hassle, turnkey solution, I recommend picking up a refurb D2 from LaCie... and as a bonus, it does lightscribe discs as well.
http://www.lacie.com/products/clearance/products/?id=10008
I just picked one of these up a few weeks back. I did a head to head comparison speed wise with my NEC 3550A, and it's actually a little bit faster. Which means it's very fast. Comes with lightscribe software, toast (lite) and a few other programs I'll probably never use.
But, for $79, it's not a bad price. Especially being able to do lightscribe on my mac...
<edit>
Compared to the model that sits in your iMac, this would be 40 bucks cheaper, while being twice as fast at burning both CD's and DVD's.
side note: no, I don't work for or with LaCie... I've just been really pleased with the drive I bought from them, even more so than the NEC 3550A I threw in my eMac last year.