In your Start menu, right-click on the Adobe Extension Manager CS3 and
explicitly Run as administrator or they won't install properly under Vista.

I had trouble installing the Kuler extension, but Rolinstone solved the
problem here:
http://pixelfumes.blogspot.com/2007/...ler-panel.html

That should fix it. It worked for me on a couple of extensions. I'm using CS3
on Vista Home Premium.