YIp everything you download, and note your pc is downloading even when just on deskop, or on a chat room or using msn.
There are programs which monitor useage, its amazing just how much you use, I myself and my GF are always online, as she moderates a Chatroom, and I am working on design and editing dvd's for a family friend so bandwith useage is maxed on 1st day of the cap