My PERSONAL recomendation to you is to install SEVERAL forum scripts and decide which you like based upon ease of sinstallation/updates, price, functionality and appearance. That's EXACTLY what I've done. My favorite, beating out vBulletin, YaBB SE and others is phpBB 2. It's currently under development, but works just fine in OS X since 2.0 RC 3. You can find it, and many others, at SOURCEFORGE.