Externals DVD burners always cost $50-$70 more than internals. Depending how much you expect to use it with your laptop, you should decide whether the higher cost is worth it.
If you go with an external, your choices will be limited because your motherboard doesn't have Firewire (unless you have an adapter card). You'll need a USB type DVD burner. Not because I have any experience with it, but because it's nicely priced and convenient, you may want Lite-on's SOHW-1693SX Black for about $110. Lite-on seems to do reasonably well in their designs. Sony sometimes lets Liteon build DVD drives for them, and puts the Sony stamp on it. There are a few other external drive choices, but with the exception of one that burns much more slowly, they are more costly.
If you pick internal, you'll have a lot more choices. Many of them are good performing and nicely priced, but not top quality DVD burners. I think you have to pay more if you want top quality. When I bought my Plextor PX-716SA, I based my choice completely on Ian's review, which seemed to conclude that it (actually PX-716A) was the best drive around. My second choice would've been Pioneer's DVR-A09(XL). Based on Ian's reviews, most of the drives around $50-$70 seem to have some trouble with particular brands of DVD-/+R, so you would need to be selective about that. I think you could be happy with almost any DVD burner if you pick the right media. There are lots of posts about DVD burner and media comparisons if you want to thoroughly research the topic.