mpeg streamclip should work.
on mac though, you’ll need flip4mac player to read/write a wmv, and if you want to create a wmv longer than 30 seconds, you’ll need to pay for flip4mac studio pro.
if you are using windows, windows media encoder may read mp4 (it obviously writes wmvs).
also, if you are using windows and cs4, adobe’s media encoder (that should have come with cs4) will read mp4s and create wmvs.
Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW