Video editing software like iMovie, for Windows?
I've not used it, but Microsoft makes Microsoft Movie Maker. It might meet your needs.

There are also some open source video editors you might have luck with:

ShotCut - http://www.shotcut.org - kind of new, might be buggy

Blender - http://www.blender.org - it's a 3D modelling app with video editing capabilities

Lightworks - http://www.lwks.com - there's a "buy" button, but there's also a free version, as I understand it.

If you don't mind using Linux, you can also try out OpenShot and Kdenlive.