Hi My current farm comprises of Windows 2003 R2 (x86) running XenApp 4.5. I need to add a Windows 2008 (x64) server to my existing Citrix farm. Are there any issues with mixing OS versions??? The Windows 2008 server will only be used to publish a single application. Will the 2008 server become a preferred ZDC due to newer OS version or can I safely mix OS's? Thanks Ang