From http://open.silverstripe.org/ticket/6006

http://msdn.microsoft.com/en-us/library/dd938878.aspx

From my testing on Windows mobile emulators they prefer commas to semi-colons so I added to my template:

<% if IsWindows %>

<% else %>

<% end_if %>
and the below to MobileSiteConfiguration?:

public function IsWindows() {
return MobileBrowserDetector::is_windows();
}