Media Player 9 and .WMV Files

Made movie w/WMM2, joined Web hosting site, some family
cannot play - only hear music - no video - forum member
suggested asking everyone to upgrade to media player 7.1
or higher because that worked for him in another
situation - some family members have XP which would have
come with Media 9 and same thing happens when they try to
view video - music only - Movie Maker 2 creates videos
in .wmv files - do they need to be encoded?? and would
doing it from .wmv to .mov solve this problem? I have XP
and upgraded my Player with the free Plus available to XP
users could that be why I can play it and other XP's
cannot? Still need to know how to tell non-XPs how they
can view videos. THanks, s