Many (most?) large providers use TR-069 in the CPE that they provide. This is how they push out firmware & config updates and provide some managed services to SoHo customers.

You might be surprised at how much a provider support rep can see with this. Here's two screenshots from Cisco's product to give you a idea: http://images.newsfactor.com/images/super/larger-12-ClearAcc... http://cdn-static.zdnet.com/i/story/60/01/072589/clearaccess...

Moral of the story: Use the most basic cable/dsl modem that they'll give you, make it as close to bridge mode as you can, and use your own router.