https://www.dotnetzone.gr:443/cs/blogs/birbilis/archive/2008/12/03/silverlight-1-0-instead-of-2-0-as-optional-windows-update-at-vista-business-sp1-x64.aspxI recently installed a Vista Business 64-bit SP1 at a client's machine and after installing all critical updates using Windows Update (or Microsoft Update in fact, which can replace Windows Update [without the user noticing any difference] also checkselCommunityServer 2.1 SP3 (Build: 20423.1)