I can back up 8 gigs on my 4MM DAT tape or write them to my DVD-RW up to 4.7 gigs. But I don't think my database will ever get that big!

Plan ahead on your database. If you are going to imbed images (recommended) then make them small JPG with high compression. If you want High Quality images, use a link to the images. This way you can backup up the large Image files separately. The database itself should be rather small without images.