I have a set of forums up and get hammered daily with spammers. I've beaten them all using SMF, two addons, and logic questions.
I use httpBL and OS & Browser Detection as my two addons. httpBL also leverages Project HoneyPot, which is real nice. They're both stable and stop a majority of the spammers outright.
I also use a logic question that cannot be solved by bots. In SMF you can ask questions and receive answers during registration. One question can be something like "Write the answer to the first question here again." A bot cannot understand that, and you can always change that question to ask for the second or third answer. I've also asked for answers to be spelled backwards and numbers to be spelled out. It stops 99% of the bots out there. I think in the past year I haven't gotten a single spammer registered with a constant 50 attacks per day.
I'm running SMF 2.0.2 but I think the mods will work in your version.