Microsoft have released a new version of the free Visio Viewer ( see http://blogs.office.com/b/visio/archive/2012/11/28/download-the-free-microsoft-visio-viewer.aspx ), so you can now view Visio 2013 files, in addition to earlier versions, without having Visio installed. Or, as in my case, on a PC that has Visio 2010 installed.
Even better news is that my visViewer product ( see http://www.bvisual.net/Products/visViewer.aspx ) works with it, without any changes!
