About those WIM2VHD videos... what's a good video editing tool?

So, I know that I've been promising everyone some new videos explaining some of WIM2VHD's features.  And I really have been working on them.  I have most of them captured, but editing them... is not going so well.

I've been using Windows Movie Maker on Windows Vista to make the first few videos, but the quality turns out to be pretty low, and it's hard to read the text on the screen because the of the bad quality.

So I have a question for you guys. What's a good video editing software package that's free or inexpensive, and can make high-quality WMV files?