Meh, any forum I know of has migration scripts to migrate from phpBB. SMF's for example, all automated and quick quick. I don't really like phpBB, experience too many bugs, especially with unread post markers, they seem to reset to "everything has been read" randomly, thus not knowing what I have not yet read (I don't always read everything in one sitting). SMF and IPB have been the only ones I've never had bad experiences with, but since IPB now costs money, I go with SMF, converted 8 sites thus far from phpBB to SMF after showing them why, havn't done so in a year now though, got to busy.
Either way, the captcha extension for SMF is on their site (SMF mods are packages that are auto-installing through the forum adminCP, no code hacking needed and is always discouraged, most extensions can be downloaded from the official mirror available inside the adminCP, but the package itself is a zip file with easy to understand xmldiff scripts), I could find the direct link if you wish, but if the license is compatable, could always use that captcha here after code converting some things to phpBB. That captcha I've yet to see bypassed by bots, and is easy to read, with a vast amount of configuration options.
