If your are having a limited (Eg 4gb per month etc) internet in your home then it would be a hard time to browse or download any stuff without exeding the limit ! Earlier i had to pay extra for my extra usage !
But now no fear ! Because i am check my usage easily ! Check this out:
NetWorx is a simple and free, yet powerful tool that helps you objectively evaluate your bandwidth situation. You can use it to collect bandwidth usage data and measure the speed of your Internet or any other network connection. NetWorx can help you identify possible sources of network problems, ensure that you do not exceed the bandwidth limits specified by your ISP, or track down suspicious network activity characteristic of Trojan horses and hacker attacks.