Cactus プラグインダウンロードできないだねえ。
どこかに落ちてないかな。 　

http://jakarta.apache.org/cactus/integration/eclipse/

The Eclipse plugin is a work in progress. In the past it was working, but since we
moved to the new Ant integration it has been broken. This requires a rewrite of the
plugin code to fix. In the meantime, we have removed the plugin download. Sorry
about that. Any help will be much welcome.