If you have a desktop computer a good DVD burner runs $26-30.
If you have a laptop, life gets more expensive. Prices run from $60 and up. Or you can buy a desktop DVD burner and put it in a cheap USB adapter case and run it external to the laptop for between $40-50 ($26-30 for the burner + $15-20 for an external USB case).
Check out newegg.com and possibly meritline for a cheap case.
No.. a CD Burner is not the same as a DVD burner - your "upgrade" would require ripping out the laser, the motor, and the control board and replacing them.. in which case, you'd be buying a DVD burner to get the correct parts anyway.
Correct, you'd need to buy a new drive amigo. There are certain pieces needed that you can't just enable. I have heard of certain drives that you can speed up using firmware, but I haven't heard of any that are able to burn dvd's with a firmware upgrade.
You will need to buy and they are pretty cheap these days.