There is a mod called Multiple Forum Mod for smf and it allows you to have two boards but share users, database, and one upgrade only!
Link: 
http://custom.simplemachines.org/mods/index.php?mod=2137Install the mod on this board then in the admin panel go here:
# Administration Center »
# Modification Settings »
# Create New Subforum 
Fill out the information like so:
This Forum's ID: 0
New Forum ID: 1
New Forum URL (WITHOUT THE TRAILING '/' !): http://twcclassics.com/forums
New Forum Name: Twc Classics Forums
Now the code that it gives you should be made into a index.php file.
Upload that to : 
http://twcclassics.com/forumsYou can add Categories to the sub-forum
Go here in the admin panel:
    * Jorgen's Community »
    * Administration Center »
    * Boards »
    * Modify Boards
Click on a category's modify button. You will see: 
Forum Parent
The ID of the sub-forum this category is usable on 
If you put 0 it will be on Twc Today's board
If you purt 1 it will be on Twc Classics' board
Tell me what you think!