Originally Posted by $5 submissions

Vbulletin and get VBSeo installed as well.

Get keywords for the forums from wordtracker and either seed the forums with medium or medium to heavy search terms and stock it with "core" articles for faster viral growth.

Hire cheap forum posters, I can help you on this for free if you wish :D and pay only per post and based on the quality you expect

Ask them to respond to your seed articles and threads for better SEO or you can even have them quote your threads on other forums they post on (warning: might attract some haterz lol )