probably need to do
http://forums.winamp.com/showthread....=1212729#clean as no way should the desktop client by playing what is a one-time install clip (aka branding) unless some crap like ccleaner is present and wiping out settings, etc as it's been known to have a tendency to do.
as for installing visualisations, no one can answer that as no specifics has been provided on _what_ is trying to be installed (though i'd guess it's presets and then that will require extra interaction).