I've seen many designs with white text / dark background - many times they look great. Nice. Yea, great eye-candy.
But, did you know it can hurt conversion?
In your case (as a forum admin), this means lower registrations, less threads, less comments, decreased pageviews, less clicks, etc
Here's a great illustration why you should reconsider your white text on dark background design...
http://www.ironicsans.com/owmyeyes/