XML/XSL free editor (eclipse plug-in, if possible)

Hi,

   Does someone know a good AND free xml/xsl editor? It should have at 
least xsl code-assist, automatic xsl transformation, code highlight and 
means to call up any browser from within the program itself.
      I tried to install some eclipse plugins, but they're all for the 
2.x version, and they didn't work with the 3.x eclipse version.
      Currently, I'm using Butterfy XML editor, but it has a bug with 
firefox, so it can't call it.
thanks