I want to be able to share stuff with my roomie over our apartment Wireless connection but currently it is not possible. Is there a router setting that will make it available for us?
Aslong as you're both connected to the wifi then usually that is enough (ie the router has given your 2 machines IP addresses in the same subnet).
The rest of the configuration is done within Windows, what versions are you using?
Both machines will need different names (Right click
Also check within Windows 7's 'Network and Sharing Center/Advanced sharing settings' (Control Panel) for 'Network discovery' to make sure it's switched on, also turn on 'File and printer sharing'. You could also turn on 'Public folder sharing' but is shouldn't be needed once everythings working.
You will finally need to make sure that each user has a username/account on each PC, even if they only use their own conmputer - any access to shared folders on the other PC will use their locally logged in credentials for access.