If it's for long-term storage, let me point out that you see a lot more posts about failed USB drives here than about failed DVDs. As Godiwa wrote, the USB drive is good to more data. I won't depend on them for long-term storage.
Yea long term storage go with a DVD writer, you can actually backup far more than 8GB by buying additonal DVDs. CDRs/DVDRs do not last forever though, if this is for long-term storage, I would re-write them periodcally and keep 2 copies.