I has an idea.
"Hack" the site, delete who you don't want to spam up the boards, and then "fix" the site and start with a nice new sheet of paper. A dirty trick, but it has potential.
Getting to work building a supportive community, unfortunately, has to start from the bottom up. It's kinda hard to tear yourself out of the vicious cycle when the cycle isn't even remotely under your control. I don't mean that to rag on you, but the simple fact is that the moderation situation here doesn't have any control at all over the stuff that goes on here. I don't think I've ever said that the moderation here's too strict -- just that it was occasionally misplaced. Here is the opportunity of a forum-time to clear the slate and try rebuilding the community that used to be XMS.