TheMadScientist - 10:46 am on Oct 24, 2012 (gmt 0)
What Andy said, and if they're not your links, then I wouldn't stress on it ... Counting inbound links from external sites against you would make it too easy for a competitor to tank you or any site they felt like, and my personal experience is they don't count against you at all, but might well count against the site containing the links.
One thing I would add to what Andy said is whether the originating link(s) are on your site or not if they don't go to a page with content that was Moved to a different location, meaning you have a page with 'essentially the same content' as the page the link points to had on it, Do Not redirect the links.
If there's no 'essentially the same' content as a link points to on your site:
If the links are on your site, simply remove them.
If the links are not on your site ... And you're feeling nice, let the site containing the links know they're broken. Or if you're not feeling nice (or maybe they're on a competitor's site) then don't do anything.