I\'m trying to install a platform but when I open Android Manager then I click Available Software then select the https://dl-ssl.google.com/android/repository/repository.xml
All that was necessary for me, a Ubuntu user, was to change the owner of the ~/.android directory. In a terminal type the following command:
sudo chown -R username:username ~/.android
Obviously, you must replace "username" (twice) with your username.
I wasn't sure if I should post this as an answer because the original poster's question was concerning Windows Vista, not Ubuntu. However I found this post whilst searching for the answer on Ubuntu so I believe it is pertinent. I don't have sufficient reputation to comment on +Maher Gamal's answer, though, which is what lead me to this answer. Hopefully someone else finds it useful!