I'm trying to Import a video into Windows Movie Maker. It's an MPEG - 4 Video. I keep getting this message everytime I click Import...

"The file C:\Documents and Settings\Buck\Desktop\New Folder (2)\SMOV0003.ASF cannot be imported because the codec required to play the file is not installed on your computer. If you have already tried to download and install the codec, close and restart Windows Movie Maker, and then try to import the file again."

I have the following Codecs installed already but I still recieve that message.

FFDSHOW AUDIO DECODER
AC3FILTER
DIRECTVOBSUB (AUTO LOADING VERSION)
NERO DVD DECODER
NERO VIDEO DECODER
DIVX DEMUX
DIVX DECODER FILTER
SHARP G.726 AUDIO CODEC
FFDSHOW MPEG-4 VIDEO DECODER


Which Codec would you recomend to fix my problem and where can I get it?

Thanks
Mike