I have Eclipse (Indigo Service Release 1, Build id: 20110916-0149) running on Win XP.
I\'ve added https://dl-ssl.google.com/android/eclipse/ and installed 4 plugins
I tried everything and nothing worked until I made my JAVA_HOME and PATH point to my JDK 6, they were pointing to the 5, then before installing the ADT plugin, make sure Eclipse is using the JDK 6 in Preferences/Java/Installed JREs. Of course make sure you are running/installing everything as an administrator.