It seems that in the public Windows 7 (The next great version of Windows) RC, they old Windows Movie Maker program is not included. There is a download of a Windows Live Movie Maker, bit is a vast different program which has little features of the older viesion.
The team say they are planning a bigger better version down the road and that this is only a beta version which is not feature complete. While it may end up being a better program a few years from now, what are you to do until then if you have switched over to Windows 7 already?
Here is an article talking about the issue:
http://on10.net/blogs/sarahintampa/Miss-the-Old-Movie-Maker-Get-it-Back-on-Windows-7/#Page=2and here is the link to download the latest version of the original Windows Movie Maker with all its features that even work on Windows 7!
http://www.microsoft.com/downloads/details.aspx?FamilyID=D6BA5972-328E-4DF7-8F9D-068FC0F80CFC&displaylang=en