Remote Desktop Connection 7.0 client update for Remote Desktop Services (RDS) for Windows XP SP3, Windows Vista SP1, and Windows Vista SP2
http://support.microsoft.com/kb/969084

Remote Desktop Connection Software (Terminal Services Client 6.1) for Windows XP
http://support.microsoft.com/kb/952155

Remote Desktop Connection Software (Terminal Services Client 6.0) for Windows Server 2003
http://support.microsoft.com/kb/925876

Remote Desktop Connection Software (Terminal Services Client 5.1.2600.2180) for Windows 2000, Windows 95, Windows 98, Windows ME, Windows NT
http://www.microsoft.com/downloads/details.aspx?FamilyID=80111f21-d48d-426e-96c2-08aa2bd23a49