By converting your movies to a more enduring format, you can ensure your movie collection survives the death of the machine that plays them.
The process is simple in principle but excruciating in practice, thanks to the complexity of the technology, the myriad of applications needed and the predations of an industry that doesn't want you format-shifting at all.
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What You'll Need
* A Windows machine with a fast processor
* An HD-DVD drive
* A Blu-Ray burner
* 30GB of free disk space, at least, though 40GB or more is recommended
* An internet connection to download all the software you need
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Alternative methods
One can also use a HD capture card with component video inputs to slurp up the output from the Xbox 360's HD DVD player. Install video capture software, hook up the player to the capture card, and go. Watch out for disk space!
More:
http://howto.wired.com/wiki/Convert_Your_HD_DVDs_to_Blu-Ray