Maybe a bit OT: MySQL forum recommendation?

My apologies in advance if this is a bit off topic, but...

On a rather old site we have a dreadful old bulletin board system
based on Matt Wright's WWWBoard - all horrid text files and ancient
Perl code. We want to replace that with a decent forum system based
on MySQL and PHP, but there's no money so it'll have to be a free
one. We also need to be able to roll it into our existing database by
adding more tables, rather than adding a separate database.
Naturally, the easier it is to set up the better. And the real icing
on the cake would be to find a script for converting between WWWBoard
and whichever one we choose, though I suspect that might be too much
to ask. I should be able to roll my own converter script if need be.

The host we're using has PHP 4.3.10 and MySQL 3.23.56, so that rules
out some I've found, but these seem promising from a quick look:

FUD Forum
miniBB
phpBB
PunBB
SEO-Board
Simple Machines Forum (SMF)
Vanilla

Any recommendations from among these or others?

--
Cheers... Chris
Highway 57 Web Development -- http://highway57.co.uk/

Anyone who is disturbed by the idea of newts in a
nightclub is potentially dangerous.
-- Frank Zappa