I got my eye on this one, think I'll grab one soon:
http://www.newegg.com/Product/Product.aspx...N82E16822136227
That FreeAgent looks good, although most external HDDs have to have a separate power cord/brick, the one above gets power thru the USB cord, only one like it I've seen so far. Backing up to DVD isn't a bad idea but they suffer the same shortcomings of any other optical media, scratches get you a nice coaster and not yer data. Of course I've also heard that hard drives are more prone to failure than any other component (in my experience they aren't mebbe I'm just lucky), so your best bet is not to put all your eggs in one basket; cram as much as you can on your pod, keep a copy of all of 'em (ideally) on your hard drive and back it all up once in a while to an external, you should be good to go.