I had a collection of about a dozen HD-DVD's, including the Harry Potter box set. I used to play them on an HTPC with a dual format drive, using totalmediatheater. My HTPC died so I built a new one. When I tried to reinstall the old TMT, it would no longer play any discs. The software is no longer supported and patches no longer available. At that point I just donated my HD-DVDs to goodwill since they were unplayable. I knew that would happen sooner or later. But all the movies I had are like $7-$8 blurays now so it's not to bad to rebuy them as I want to watch them. I don't know what I would do with a hundred HD-DVD's. You could try selling them but good luck with that. You're probably better off just donating them and getting a tax deduction back.