How can I find out if SP1 has been installed on a server which has .NET 3.5?
Check is the following directory exists:
In 64bit machines: %SYSTEMROOT%\Microsoft.NET\Framework64\v3.5\Microsoft .NET Framework 3.5 SP1\
In 32bit machines: %SYSTEMROOT%\Microsoft.NET\Framework\v3.5\Microsoft .NET Framework 3.5 SP1\
Where %SYSTEMROOT% is the SYSTEMROOT enviromental variable (e.g. C:\Windows).