Agreed, Mark made some good suggestions. Do you have a router of some kind splitting up your internet connection to multiple devices? It sounds like you do. If so, most of them have a web interface that allows you to configure them. It may also allow you to keep tabs on bandwidth.
To find out, try this:
1. Open a command prompt (Start, Run, cmd, Enter) or under Accessories
2. Type: ipconfig then hit Enter.
3. Note the IP of your gateway. This is usually your router's IP address.
4. Open a browser window and type in that IP. You may need to change the beginning from
http://IP to
https://IP. Some WiFi routers will also not allow this from a wireless device. So try it from a wired computer.
5. It should prompt you for a name and password. Once you're in, you may find a way to see what IPs are using all your bandwidth at any given time.
Another individual PC idea would be to just right click on the taskbar, choose Stark Task Manager, then click on the networking tab. This will show you current bandwidth usage on that PC.
Mike