For WMV files on the Mac you can use Microsoft Media Player for the Mac or this cool little app that I just discovered.
http://www.flip4mac.com/ the app is WMV Player. Let's you run wmv files right inside of Quicktime.
A ton of pricing options, if you just want to play the files it's $9.99 All the way up to full editing capabilities for $179.99.
Factor in that you can replace Microsoft Office with OpenOffice for FREE and your a happy camper.
www.openoffice.org
Scott