To close this off, Version 5 supports .NET 4.
Built on .NET 4
Provided as a native .NET Framework 4 application, support is now provided for advanced users wishing to reference the latest .NET dlls whilst maintaining the compatibility for installing the application on a wide range of modern and historical operating systems including Windows Server 2003 and Windows XP through to Windows Server 2012 and Windows 8.1.
Cheers,
Nitin