"OOPs! Forgot to Keep a Copy of Movie Maker 1 - How Can I get it Back?
There are so many computers around that are running Windows XP and most of them haven't moved to Movie Maker 2 yet. Take a floppy disk to one of them and copy the main executable file, the one named moviemk.exe in the C:\Program Files\Movie Maker folder - it's only 807K in size. Rename it on the floppy to something like MovieMaker1.exe, and then move it from there to your Movie Maker folder with MM2. Make an icon to it for your desktop and run it as needed.
You can then run MM1 and MM2 as needed. I've gone as far as having them both open and previewing the same MM1 project file at the same time, using the same source files, and haven't run into any conflicts. But, when you edit a project using MM2, you won't be able to open it again with MM1. Backup your MM1 project files first."
Source - click here (click on Software > Setup in the left-hand frame)