It depends on what you are doing with the laptop. If you are only doing Internet and email, you can get a lightweight laptop with less horsepower. If you need to do hevy work and need alot of processing power you will also need more cooling from fans and the fans will need more power from bigger batteries so the weight will increase. You can get good laptops from between 2.5 to 5 pounds. Use the keyword "ultraportable" when searching.
We're looking at buying a Dell Lattitude X1. It weighs a mere 2.5 lbs, 12" screen, etc. Of course they've sucked everything out of that they could. If you want DVD then that's separate. It has a 6-cell battery but it depends what you're doing on how long it will last.
i prefer DVD not to be in notebook. it doesnt make sense because i rarely use any media, once per month maybe. the lighter the better. i dont need if for playing games, just for checking stats, checking bank accounts, sending emails and visiting websites & forums.