Service Providers Could See P2P Backlog: "ISPs often 'oversubscribe' their networks by a certain ratio -- 40-to-1 is typical -- which means they don't actually have the capacity to handle all of their users simultaneously.

So, if most computers on an ISP's network stay constantly connected running a P2P application like Napster - chewing up bandwidth by serving up files or otherwise communicating with other peers in the network -- the original ISP usage model will be shattered."