I’ve had experiences with LG DVD burners and all i can say is don’t get one.
I don’t know if it’s just me or bad luck but i have now gone through three LG burners in a year, they just can’t cut it. If i were you, i’d go and find a burner from SONY or go grab an ASUS DRW-1608P2S, it’s one of the fastest drives on the planet and will read and write every format known to man.
I would not recommend an external drive unless your on the move alot and need your burner with you at all times.
The ASUS drive i mentioned however does happen to come in an external format (with both IEEE1394 and USB to choose from).
I cannot comment on any other drive than LG (mine is GSA-4160B)
It is the first and only DVD-RW (and RAM) which I ever owned and it is and has been brilliant.
Never had a problem.
If I were you, I would try and go for the Firewire rather than USB.