We are talking about "certifying" not just functioning! Mountain struggled with every new OS release both on desktop and server. It was only the merger with Meridian that brought Microsoft Gold Partner status, ie they bought it rather than trained for it. A year ago of their customer base of around 500 firms it was estimated they had less than fifty sites on .NET, and at the conversion rate of one a week they IRIS would have to extend support until 2018!