Did you ever have the need to use different versions of Microsofts Visual C++ compiler from the command line? Did you wish you wouldn’t have to constantly call vcvars32.bat or change your environment (PATH, INCLUDE and LIB variables)?
In comes a little tool called envvc.exe. It sets the environment for the chosen version and then calls any chosen executable. As additional feature it verifies that you have installed the latest service pack for the chosen version.