Or replace the DVD-RW drive with a Bluray-Rom/DVD-RW drive. Depending on what brand/Model your laptop is this from Very simple (ie remove one screw) to nie onto impossible. Did this to 2 toshibia Laptops, one used the Old PATA (IDE) interface and the slightly newer one used a SATA drive. Anyway cost is around $100.
Advantages - Portability, do not have to lug around the "external" Drive.
Brett's method - Allows use on more than just that laptop as it can be shared with other computers. Also Cheaper $50 and up.