Thanks Tris, done that and WMM is seeing the codecs now. Still only showing WMV files as video. It doesn't appear to support MOV files - but MPG it appears to be seeing them as audio files as that's the only place it allows them to be added to the timeline.
Vexed. Will keep trying when the nippers are in bed.
If I were to abandon my initial criteria of the software being for total beginners, and legit, what options do I have. Suspect Adobe stuff might be overkill.