completely agree with sam9. but before you do this i would talk to the hosting company and tell them what you plan to do. and while this is a great idea, you cannot forget, if you want your forum to grow, that you have to leave room for everything to grow. you dont want to limit yourself too much in what you buy as your hosting package. if you do do this, you may be screwing yourself. so be sure to get the package that you need but also leave room for improvement.
good luck to finding you hosting solution.