Hey Ed,

Here's a couple of articles from Microsoft that might help or shed some light:

http://support.microsoft.com/default.aspx?scid=kb;EN-US;823770

http://support.microsoft.com/kb/306318/EN-US/

http://support.microsoft.com/kb/306331/EN-US/

This one is good...XP comes with a utility that checks to see if you've got a DVD decoder installed and if it needs an upgrade.

-mike