No one can answer this question for you but you....
Personally my DVD because I use my DVD player (to watch my DVD movies collection) at
least 15 movies : 1 CDR burned. I haven't taken details stats of this sort of thing...but I would say 25 or 30:1 is probably more reasonable. But bare minimum 15:1.
I don't pirate software, I back up important data, and occasionally make a copy of a really important CD, or make Win2k SP slipstreams...that's all the use I have for my CDRW, so it's an easy choice to me. I can easily live without any of it, or borrow a CDRW once in a while when I need it.
My roommate on the other hand can go through two or three 50 stacks (of CDs) in a good month, and would never use a DVD drive (if he had one, which he does not).
But how much do you want to watch movies on your PC compared to how often you will burn CDs...
No body can answer this for you but you.
Personally though defiantely a DVD rom.
Though, after having used a 10x Pioneer DVD and a 12x Toshiba, there is no way in hell I'd take the Pioneer over the Toshiba
(Just a personal preference, I'm not suggesting you avoid the Pioneer, on a board this big you will find several users that love and several that hate any given product)