Q. In my Microsoft-based VDI environment, I have single sign-on (SSO) when I connect from my Windows 7, clients but when I connect from Windows XP, I have to authenticate on the session host and the XP VM. Why?

A. SSO support is part of the RDP v7 protocol which is the standard in Windows 7 but is not standard in Windows XP or Windows Vista. To enable SSO, you must install the Remote Desktop Connection (RDC) 7.0 client update, which supports Windows Vista SP1/SP2 and Windows XP SP3.

RDC 7 has support for RDP v7, which includes SSO and other VDI functions. I highly recommend it.