Access to a single server and update servers for AV and Comodo. Nothing else.

I need to setup a machine to only access a single server on our LAN plus be able to download windows updates, msse updates and comodo updates. There should be no internet and no access to any other machines. I’ve found tutorials here that show how to block internet while allowing LAN, but I’m having trouble with allowing the update sites. Can someone point me in the right direction?

I had not yet tested the settings from the tutorial when I sent my original post. I have now and it just doesn’t seem to work. Here’s the link
http://help.comodo.com/topic-72-1-206-2816-Blocking-Internet-Access-while-Allowing-Local-Area-Network-(LAN)--Access.html

It appears to be straight forward enough. This is how I set mine up -
from step 5 I set the source address to the IP of the computer (the XP machine I’m currently configuring Comodo on)
from step 6 I set the destination address as the network zone of the server, which is just a single IPv4 address.
Everything else is as described in the tutorial.

With this I can still surf the web, but I cant access my server. I’m probably missing something simple.

Thanks for any advice you can offer.