SMF = Simple Machines Forum
You will need to install SMF in order to convert WBB to SMF. SMF install
The convertor for WBB to SMF, Convertor
The convertor for SMF to phpBB3, [BETA] SMF 1.1 to phpBB3 Convertor
The convertor for SMF to phpBB2, [SUPPORT] SMF 1.1.1 to phpBB2
phpBB3 is more advanced than phpBB2 and has more features. For a feature comparison, Features
phpBB2 may have more MODs available at the present time, but that is only because phpBB2 has been around a lot longer than phpBB3. There are more MODs becoming available for phpBB3 every day.
Support for phpBB2 will be ending 1 January 2008.