As I've previously said I don't own a Zune.
But this is a community and I'd like to help you as much as I can.
So I've done some research and this is what I've found:
Zune currently
works with:
WMA, MP3,
AAC for audio,
WMV,
MPEG-4,
H.264 for video
and JPEG for pictures.
So you'll have to convert it
Zamzar it's an online free tool for doing that