Capture is only any good against spambots, and even they are getting through these systems now. To be honest it's a waste of time..
Spam farms are growing big time now, and thousands of people are now employed to sign up and spam websites. They being human, can get through the capture.
Rather than inconvenience the members of this site, the capture should be done at registration, not afterwards.
Not sure what anti spam mods they have in place, but it would be handy if when registering they were checked against the stopforum spam or project honeypot databases first.