Very Easy! Only hard part is opening your iMac
Hi there:
It is actually very simple. Go to ESbuy.com or shop4tech.com and order a bare drive Pioneer DVD-R 105 or DVD-R 106. I would go with the latter if you can afford it, because it supports both DVD- and DVD+.
I did this recently on my G4 tower and it was a cinch. Make sure, however, you do not have a copy of iDVD on your HD before installing the new drive (I know you should not, but a friend of mine with no SuperDrive downloaded a copy of IDVD 2 from Limewire just for ****s and giggles and installed it. When we installed the SuperDrive, System Profiler would not recognize it. After we erased all remnants if iDVD 2 from his system and rebooted, everything was fine.) Anyway, pick yourself a copy of iLife and install iDVD 3 AFTER you install the SuperDrive. Now you're ready to burn, baby burn!
Now, opening your iMac and dicking with it is FAR more complex than my G4 tower. Pick yourself up a copy of the current MacWorld magazibe. They have a step by step tutotial on how to open your iMac safely and upgrade it. Or do dome on-line research. But I would recommend getting the Mac World mag; their tutorial is very complete and the photos show you exactly what to do. Hell, it might even be available on-line.
There you go! Weird: I was a potty mouth in this post. Normally I am not friggin' like this!