Just install this plug-in, no configuration needed. After installation it should work. So when Winamp is closed, the Last.FM Audioscrobbler will be closed automatically, too.If the plug-in doesn't work and isn't shown in the plug-in list you have to install Microsoft Visual C++ Redistributable 2008 9.0.30729Download it here: http://www.microsoft.com/downloads/details.aspx?familyid=A5C84275-3B97-4AB7-A40D-3802B2AF5FC2
This is provided untested. It may also require the .NET framework to be installed (in addition to the Visual C++ 2008 redistributable mentioned.