I had been thinking about getting an external hard drive for my laptop to back up all of my digital media. but then after doing some math, I realized that external hdd space costs about $1 per gig, while a single layer dvd holds basically 5 gigs at a cost of 50 cents. so basically it seems that hard drive storage space costs 10 times what it does to burn something to a dvd. now I don't have a dvd burner yet, but I'm planning on getting a new computer in a little over a year, and a dual layer burner in that one. is there any reason to prefer an external hdd to storing info on dvd's/cd's?