bathory told you right though. You just go into File Associations(I'm assuming you're using either Gnome or KDE?) and search for HTML. It should give you a couple of programs that can handle it. Go to edit Mozilla and just put in the command bathory told you above.
I think my exact command is this
Code:
mozilla -remote "openURL(%u, new-window)"
but I read that the other one works too.