I don't mean to be rude and tell you how to run your blog but I know many are with me when I say this, word verification is a PAIN!. When I see those little boxes my heart sinks, it usually takes me several attempts of clicking on the refresh button to even see the words and numbers I'm supposed to be typing then I will type them in only to see it's failed and I have to start all over again, it's very frustrating to say the least, sometimes I have to just give up. Then sometimes I leave a comment and move straight on to the next blog only to discover later that my comment hasn't been published because word verification was present and I hadn't seen it.
I have had a problem with spammers lately so I enabled comment moderation for a while and deleted the particular post that was attracting it and have had no problems since.
For those who don't know how to do it, First click on settings and then posts and comments and you can turn it off there.
I know many of you are of the same mind please read Theresa's post on the subject here it says it all.