I have looked at some Ipod forums but am still not that clear about this matter and this forum seems to give a more clear and coherent answer.
Basically, If I have downloaded an Mpeg file from somewhere (as a hypothetical experiment with no copyright issues

) and it shows on the desktop as 'Windows Media File' can this be dragged and dropped into the Ipod library or does it have to be reformatted into another file type in some way?