Forum Domain re-directs
 

Google webmaster tools tells me that I have two sites; http://www.businessadviceforum.com and http://businessadviceforum.com. I want to use the www. domain only.

How do I fix this in a way that won't inconvenience my members or make it difficult for them to log into the forum? I also want to make the change in such a way that it doesn't negatively affect our SEO.

Thanks!