WARNING: Make sure you've backed up your system before attempting this fix.  This may or may not 
work depending on the hardware found in your computer.


Here's how to get it to work:

1) Go to a Windows XP machine, and find this file:
C:\Windows\system32\mswebdvd.dll
(if you can't find it or don't have an XP machine, download this copy 
http://web.mit.edu/shakspere/xmas/mswebdvd.dll

2) Copy mswebdvd.dll to your Vista machine. It doesn't actually matter where
you put it.

3) On your Vista machine, open a command prompt in the same folder where you
copied mswebdvd.dll

NOTE: You have to open your command prompt as an administrator in
Vista. Find it on the Start menu (I think it's under All
Programs->Accessories, right-click on it, and choose Run as
Administrator.)  Use the change directory command to switch to the
folder where you copied mswebdvd.dll (cd [directory]).


4) Type the following command:
regsvr32 mswebdvd.dll

Since this is Vista, it will probably pop up a box asking if you grant
permission to do this.

After you grant permission, you should see a message that mswebdvd.dll was
registered successfully. You should now be able to open up Xmas and get it
to play DVDs.