Hmm, strange.
Don't know what those could be unless they're Raptors that were somehow rounded up to 80GB, in which case I'm guessing when people get drives with less than 70 actual GB that the'll probably be a little irritated.
Maybe give them a call or chat with someone and see if you can find out the specifics? Probably not worth the hassle but hey who knows, maybe Dell's getting into the hard drive business now. I wouldn't mind there being 10K RPM 80GB drives for $100 (well as long as they're not prone to failure and/or have a good warranty).