The MS true type fonts core fonts are available for any system (that supports TTF) to download via http://kde-look.org/content/show.php?content=19259
I'm sure they are available elsewhere but I pick most of my eyecandy stuff for KDE from here.
If you specify sans-serif as the fallback font, the users' sans-serif setting will take hold.If it's not the font you expect - well don't worry about it because that's what the user or their admin chose and you have no control over it.
"How I Learned To Stop Worrying and Relinquish Control"
http://adaptivepath.com/publications/essays/archives/000501.php
;)Cheers
James
