Why convert it at all? Why not just upload it to a place like YouTube then embed it into your own site?
If you insist on converting it, you can use either QTPro or MPEG Streamclip to convert it to mpg -- and a quick google search came up with a couple .mov to .wmv free programs, though I don't know if they are for the Mac.
To be honest, I see no reason not to leave it as a QT file -- most PC people have QT now, and you can always provide a link to the QT download page the same way people who post PDFs provide a link to Adobe so they can download Acrobat Reader.