Problems with Linksys router

Ok, heres the setup I have: I have three computers: Desktop #1, Laptop #1, and Laptop #2. All these computers connect to the internet via the linksys 4 port router that I have. Now I need to get rid of the firewall for only Desktop #1. Under the DMZ Host page (which is a part of the setting thing for the router) I have my computer's IP there (It says in the manual that this is all I need to do to get the firewall off of Desktop #1) Before when I would goto send stuff over AIM or Yahoo messenger it would give Desktop #1 errors and would say that Destop #1 cant send the file cause of the firewall, but now Desktop #1 experiences the same probs! I have no idea how to send the files. I don't have any other firewall software, and the Windows XP one I know is disabled. HELP!
If you put 192.160.x.x the x's replaced with desktop #1's Internal network IP in the DMZ host and enable it (you might haveto reboot router) it should work fine.
I feel like a moron now for not having reboot the router. Thanks guys... I love this site, I post a problem and its solved within a hour and half