Microsoft support finally finished for Windows Server 2003 R2 on 14th July 2015. The mainstream support actually finished on 13th July 2010 and the extended support has now finished this year. This is all a normal part of the Microsoft product life cycle.
It is highly recommended that any machines running Windows Server 2003 are upgraded or replaced as soon as possible. Over the years, servers have dropped in price and currently offer excellent value for money to businesses of all sizes. Released in September 2012, Windows Server 2012 is proving to be excellent and very much recommended as a replacement for old Server 2003 installations.