Javascript: Force Download?

I’m trying to make Javascript force a download, but I don’t know how. Here is my current function:


function saveFile() {
	var list = document.playerCtrl.downloads;
	var downloadURL = list.options[list.selectedIndex].value;
	window.location.href = downloadURL;
}

all of the downloadURLs are pointed to WMVs (videos) on a server. This (of course) automatically opens Windows Media Player. Is there any way for me to force a right click/save as?