I agree with leaving the non-posting accounts. I am a regular visitor at other sites, but never participate on the forum. One possible idea is if Viper can see when the last time their IP logged on. If they haven't visited the site in say, 100 days then you know they forgot about it, and maybe then you could clean up those users. But don't delete accounts just 'cause they don't post.
And I think that this most recent torrent is directly responsible for about 10 more people I haven't seen before on the forums, if not more. I think we're going to hit 3,000 by the end of the TG season, anyone else agree?