Using Movie Maker to edit MP4

I’m using Windows XP on HP laptop with Service Pack 3. I imported some videos in MP4 format from my FujiFilm Finepix S2000HP to the laptop. When I try to edit those video in Movie maker it seems like Moviemaker wont support them.

Is there any software or codec required to edit MP4 in Moviemaker? Please help.

Are you able to play those MP4 videos in Windows Media Player? If yes, then you dont require any extra codec for Moviemaker as well. Probably there would be some another problem. I would like to know just to clarify whether you say you cannot edit the