check out this post:
forget about any of the "friendly" or human readable urls SEO stuff. that simply doesn't matter to the search engines. if you want to rank better in google, you give google what it wants, relevant content.
you help google by making sure that good keywords are in the places it looks for them. the post linked above tells you have to make that automatic.
now, all you have to do is make sure that your forum/topic titles on your board are using keywords relevant to the discussion and you are good.