My laptop has a 100GB hard drive. My desktop has 750GB of storage. I have over 70 MiniDV video tapes, effectively 13GB each and representing another 700GB or so. I've got a backup problem. A big backup problem.
CD and then DVD were good backup solutions when hard disks were smaller, but now they are inadequate. Tape backup solutions are too expensive. Hard disks are cheap enough to use for backup (I saw a Western Digital 500GB MyBook Essential for $99 the other day.) They are also very fast compared to other backup media.
Optical discs, though, are convenient and very cheap. They are not mechanical and won't stop working. Archival life is not great for optical discs but being so cheap they are easily renewed every five years or so (and that renewal is essential, by the way).
I just need big ones. Blu-ray discs have 66% more capacity than HD DVD discs. For dual-layer discs that means 50GB instead of 30GB. This is a no-brainer as far as I'm concerned.
MiniDV tapes are great for archival purposes but very slow when one needs to access them. I have wanted to make master DVDs of each tape but most of my tapes will not fit on a dual-layer DVD. With a 50GB disc, I could get three and possibly four MiniDV tapes archived on a single disc, then use that disc when I needed video clips. With HD DVD, I'd get only two tapes archived per disc.
I don't care about the entertainment side of this issue other than hoping one of the two formats will quickly prevail. I got hosed when VHS crushed the technically superior Beta format and won't let it happen again. I won't buy a player and I certainly won't buy any content until the dust settles in this current format war. You'd think all parties would have learned from Beta vs. VHS. The truth is that my wife and I are quite happy with the picture quality of DVD movies and are in no rush to make a change.
My biggest disappointment in the current skirmish is Microsoft. With such a vested interest in computing, you'd think the company would also favor the largest capacity on behalf of its customers. No such luck - Microsoft is in the HD DVD camp.