Well one thing would be to not keep Limewire on always. If you just use it now and then, just keep it open for a few hours every time you use it, or even shortly after you are done downloading just check if you are uploading to anyone. If not then close it. If you are then right-click on the Limewire icon in your active tasks icons (bottom right) and choose to exit when active transfers finish.

Another thing is to disable UltraPeer Capabilities. It's in the options somewhere, sorry I can't be more specific but I don't have it installed right now.

A good way to see if it is Limewire or something else using your bandwidth is using a firewall that shows active connections. I would recommend Comodo Personal Firewall: Free Firewall Protection Software Best Firewall Computer Security Free Personal Firewall