Acer will only replace the burner with another of the same model. You can buy one of the models I linked to and bring it to them, but I suspect that the repair guys aren't allowed to put non-Acer parts in the machine. That's usually the case with prebuilt computers. As for getting a local technician to replace it, the safer bet is to ask a techy friend to do it for you. Most people who have put a computer together before should be able to pull it off. If you decide to buy the drive yourself and take it to Best Buy or Fry's, you can expect them to charge about $20-40. If they try to charge more than that, remind them that it's only 5-10 minutes of work.
The drives that I linked to are all full sized drives. I know that your current...