Look for Movie Maker 6.
It can be found on Vista discs and possibly elsewhere on line.
An advantage of MM6 that I noticed is that the frame by frame advance is only 3/100 of a second, rather than 7/100 in MM 2.6. Additionally, you can click through single frames in MM6 much faster than in MM 2.6, which has a considerable lag.
MM6 also seems to process clips faster than 2.6.
Copy the Movie Maker folder from Vista (C:\Program Files\Movie Maker) to your Win 7 Program Files folder.
Windows Movie Maker 6.0 - Install on Windows 7