rtcvb32: Digital media deteriorates rather rapidly. I remember reading not that long ago how historians who would go over letters from wars over a hundred years before, and today the data disappears in the blink of an eye, or on physical media it might deteriorate within 20 years.
If you HAVE to make a backup, i'd get a drive that's at least as big as your original, and do a direct raw copy.
As for using a digital service, it's difficult to say... Some offer unlimited space but aren't intended as a personal drive, while others let you have a few gigs or terabytes for free, and otherwise a monthly service.
It doesn't seem like a good long term solution either way. If you can afford it and the prices are reasonable, maybe get a blue-ray burner and burn 50gigs at a time until all your data is backed up... I'd also burn 2 copies, in case one gets damaged, and don't store them in the same place.
