[TomorrowsGaming]

Good question and you are also on the right path about 301 redirects since that is the best way to preserve your current Search Engine Ranks. 301 is a permanent redirect, Lets say you want to redirect http://yourdomain.com/forum to now http://yourdomain.com , meaning your old site is in the 'forum' directory and now you want to redirect it to the root or why other domain...So In this case you could simply use the good old .htaccess method.

Due to SEO we did this on one of our vbulletin forums recently and its a relatively simple process really. For example, our forum was located at http://:forums.tomorowsgaming.com, after using the .htaccess redirect, all incoming links are now being automatically redirected to the root folder, http://tomorrowsgaming.com. Here is how you would go abouts doing it..

Using the code below create a new .htaccess file inside your current directory,
eg. 'forum' , this should redirect all your incoming links and preserve your seo,

Options +FollowSymLinks
RewriteEngine on
RewriteRule (.*) http://www.yourdomain.com/$1 [R=301,L]

You are done! See, piece of cake..
After that, you can go check if your 301 redirect is working properly here http://www.ragepank.com/redirect-check/