title: Check username and password of Windows account
body: <p>I have an installation package that installs a service process that I create.  I'd like to prompt the user for the username/password of the account that the service process should run under.  I'd like to verify the the username/password combination are valid before continuing with the installation.  I have a C DLL that I am using for special installation behavior, but I can't figure out how to use the Windows API to verify an account's credentials.  I'd like to be able to support the same account name syntax used by the service control manager.</p>