Good call Jerry. My preference would be (from the DC) to query the router rather than the ISP, for various reasons (local caching, lower maintenance) but the OpenDNS project is always worth a look.
And yes Chris, I would do the change you suggested. If you wish to implement OpenDNS, I would do it at the router, not at the DC. DNS is very noisy traffic with latency issues and it's best to keep as much of it local as possible.