Joe,
Your best bet in this case is to place a appropriately sized firewall at the customer's site, i.e. Cisco PIX 501 - 515 series or SonicWall's equivalent and link it to a WebSense or N2H2 content filtering server at your NOC. the short version of how this works us The firewall sends the URL your customer is requesting to the filter server and the filter server tells the firewall whether to grant or deny access to the URL. Both products can be configured to fail hard or soft i.e. if the content server is down the firewall will either block all URL's or grant all URL's. Both products do what you want them to do right out of the box and can be tuned easily by your staff or the customer. Scott C. McGrath