Saving my music

I purchased a SimpleTech 80GB about 6 months ago. I have tried to save my music on to it and just plug it in and play my music back. I have a problem with my music not coming up and it says Windows Media Player cannot find the file. If you are trying to play, burn, or sync an item that is in your library, the item might point to a file that has been moved, renamed, or deleted. All I want is to just save my music and photos onto the SimpleTech 80GB and play my music without having to restore all of the music back onto my laptop.

When I try to sync music from my laptop media center, I get a message saying that the file has been moved/deleted etc. I'm just trying to put music on my MP3 player.