[citation][nom]livebriand[/nom]Like everyone else on the internet I'm in shock that you think anyone would actually fall for this. Did you really think that would work?[/citation]
Those are generated by spam bots, they get past the captcha by using captcha farms (there are idiots who will go on those pay sites which pay you 1 tenth of a penny for each captcha you get right (not understanding that you will probably never reach the $10 minimum payout.
Anyway more complex caphchas are no longer working because those spam companies are farming out the captcha for more or less free.
The only effective way so far that I have seen is to have custom human verifications where it will ask something like " What is 5 plus two" This reduces the ability of the spambots to farm off all of the verifications and thus will require then to customize a spam profile for the site (which can be mitigated by changing the id's of the text fields)
Another method (though it requires more moderators), is to have a comment approval system where after they register, their first post requires approval and if it is spam the moderator can easily ban the user, and if it is a valid comment then it is approved and then all subsequent post will be approved automatically.
hopefully tomshardware will one day implement a more modern spam prevention system.