Since I don't have a linksys wireless router, I can't personally say for certainty exactly how to do this, but I can say that you can block port 80 with your router. There should be a section in your settings on the router labeled Security or ACL. There it should be quite obvious what to do. Normally the screen will let you designate a port, ip address, something of that sort to either allow or deny. But that will only work for someone connected to that router. If you have other drops or anything around that office that someone can plug into, you need to find some way to run all the connections through an actual router, not a commercial router such as the one you have. Hope this works, vote best if this helps.