Why are you listening to other people? Everyone will have a different opinion on this topic. Decide what YOU need, and go with that.
DVD drives are backwards compatible with CD's. Ask yourself how you would feel if you put all your eggs in 1 basket (Combo drive), and it fails one Friday night? If you have one DVD and one CD, at least you can keep going.
If you can afford it, and need continuity, go for 2 combos/DVD's
Good Luck :wink: