Xbox 360 HD can be connected to your pc
Some Xbox scene guys have apparently released a driver for Windows XP that you can use to connect the HD-DVD drive of the Xbox 360 to the PC. The device can be used to play HD-DVD movies and contents, and connecting it to the PC may open up the possibility to do so on the computer as well. It may also open up possibilities to rip contents of Xbox discs on the PC.
All you need is to get hold of the driver which was released under the name XBOX360.HD-DVDRom.UDF.Reader.v2.5.WindowsXP-BluePrint.
You can access the complete release information on the official xbins.org website. Is it legal to use and download those drivers? I honestly do not know the answer to this. I can only foresee that it will surely be released to p2p networks, usenet and offered on irc channels to everyone who knows how to use those channels. I can't seem to find a reason why it should be illegal though.
The best way would probably be to try and get the file from the xbins irc channel on the Efnet network. Once there you join their channel /join #xbins and pull the list of fileservers from the channel by typing /msg xbins !list
Follow the information provided and you might find the tool there. I say might because I did not try that.
Update: Toshiba with its HD-DVD format lost the next generation format war to Sony's Blu-Ray format. While there are still some HD-DVD drives around, they are not available on retail channels anymore. What is even more important is that new movies won't be released as HD-DVD discs anymore, and that you cannot purchase blank discs for the device anymore as well.
What this means is that the option to connect the drive to a Windows PC is not really of use anymore, unless you own media already that you still own.