A leading question if ever there was one
, I have a souped up G4 Pismo which only came with a CD/DVD reader. When the price of CDs crashed I bought an external Freecom Travelmate, an excellent very portable (even ran off its own batteries) CDR writer.
Many moons later and the price of DVDs has crashed and I decided to get the Lacie F/W external drive. It's external, portable-ish but it probably weighs as much as the PB. I purchased this model as I wanted to be future proof for the next generation of optical disks - which I think will be the dual layer. In addition if the drive goes u/s then I recon I can strip the drive out and easily slot a new standard drive in.
So what drive do you get? I guess if you Google for internal drives I think you'll find a very restricted and costly few sources. If you can stand the extra luggage then the choice of externals is far greater at more realistic prices. What you have to decide is how much to spend and how future proof you wish to be.
My feelings on the future of optical disks is that the double sided disks are dead in the water, the next big craze will be dual layer 8Gbyte+, blue ray (20Gbte+) is on the horizon but currently very expensive with little software support.