That's kinda a tough one. Sorry -- I don't know the answer, but have heard that Windows Movie Maker, while free and from Microsoft, is rather buggy.
I think you'll have to pony up some cash to get something that's halfway decent for editing movies on Windows. Roxio Creator 2010 for Windows, maybe? About $70 after a $30 instant rebate right now.
Or see if you can edit on a friend or relative's Mac, or if you have access to an university's media lab, that's another possibility.
NOTE: I've never used Roxio Creator for any movie editing on Windows so I'm not even sure it can do that. If you're thinking about it, check it out further.