Windows Live Movie Maker and Movie Maker 2.6 are the easiest to install, as they are available as downloadable packages from Microsoft. I'll cover them in page 1 of this article.
MM1, MM2.1 and MM6 are integral parts of XP or Vista operating systems. Copying them to a Windows 7 system and making them work takes some techie dexterity, more than the average user has or should attempt. Once working, users can find themselves tripping over conflicting versions if they have more than one or two. Page 2 of this article tells you how to install them but for tech support you would best lean on someone close by.
I downloaded and installed Windows Live Movie Maker and MM2.6, using default settings. For the others, I copied the Movie Maker folders, subfolders and files from my XP-MCE (Media Center Edition) and Vista Home Basic laptops. They opened and some features worked. I then registered the DLLs which shifted them into higher gears, letting me import files, make projects and save or publish movies.
I didn't experience any crashes. Starting with a clean slate in Windows 7, I ended with five installed and working versions of Windows Movie Maker. Let's go through them one at a time.