You can also revert to the Vista version "Windows Movie Maker" (not Windows Live Movie Maker). As I recall, all you need is access to a Vista disc and then copy the files over.
Using Windows Movie Maker, the process would be:
1: Open the full length video and begin playing it.
2: Locate the desired split point and split the file. The screen now shows 2 parts.
3: Drag the first part (up to the split point) to the "time line" area at the screen bottom.
4: "Publish" the portion you just dragged to the time line. That's now short movie number 1
5: Repeat the process for 2, 3, 4, etc. Make sure that the time line contains only the short clip when you "publish". If you instead split the long movie into 5 short clips and then drag all 5 to the time line, the published movie will be the same as the original long movie--the 5 short clips will be rejoined.
I'm surprised Windows Live Movie Maker can't do this, but that may be one of the reasons why the warning went out that it was inferior to the older "Windows Movie Maker" from Vista.