Well, to qualify this even further, nobody automatically becomes an ultrapeer as soon as they connect. There's a rather extensive bunch of criteria that allows you to be an ultrapeer... most of it based on connection speed and the amount of time a system is connected to the network.

That's where ultrapeers modify the Gnutella network model slightly. Rather than everyone being a client and server, now nodes are categorized into leaf nodes and ultrapeers. Leaf nodes only maintain connections to ultrapeers. Ultrapeers maintain connections to leaf nodes and to other ultrapeers. Once you connect, you are a leaf node. LimeWire then evaluates your system over a period of time and determines whether it is suitable to be an ultrapeer.

So, to get to my point (ya, I know, I tend to ramble), you're probably not in danger of using too much bandwidth because of ultrapeer capabilities... chances are you're not an ultrapeer and checking the "Disable Ultrapeer Capabilities" box in LimeWire's options won't help conserve any more bandwidth. However, you can rest assured that LimeWire is probably one of the most bandwidth friendly clients I've seen. It uses probably 10 times less bandwidth than most other clients I've used.