I've included a flipchart that I found on Sugardoodle. I'm just going to attach the pages on the board - not use them as a flipchart, and then once the kids have sung it a few times, pass out a bunch of Kazoos (from Oriental Trading) and let them sing through those. Maybe ... we'll even march around the room with them.
What could be funner than a kazoo? Huh? Here's the link:
http://www.4shared.com/document/COsVWmze/I_Will_Be_Valiant.html