If these songs that you want to share via email were purchased from the iTunes music store, then don't do it.
You do not own the right to "share" those songs.
However, if these tracks are yours, convert them to MP3 and email that to your PC friends.
I suspect though that you have a "Rights" issue going on here.
I am wondering If there is a program to deal with the iTunes media files. I want to share them via email to my friends. but then can not open in window media player.