Rendering an animation as image files is also a good idea if the area in which you live is subject to frequent or unexpected power outages. The computer will save these in sequence and if the power goes out the files rendered up to that point will still be saved. If an animation is rendered as an AVI or QT file and the power goes out the file will probably be corrupted, and all progress on it could well be lost. The only caveat that I can see is that I haven't been able to import image files into Windows Movie Maker successfully. Maybe someone else has.