If you're looking for a free way to monitor the speed of your Internet connection, as well as the total amount of bandwidth you've used, you'd do well to download Bandwidth Vista. After its initial setup, it does a great job of reporting, and includes a few nifty extras as well.
When you launch the program, you'll see a map of the world, but it won't begin monitoring anything. So you'll have to do a setup. On the left-hand top side of the screen, click the name of your PC, then choose the connection you want to monitor. After that, it goes about its work, and shows you a constant graph of the speed of your Internet connection. It also shows on a map where the sites are that you visit.
That's just the basics--but if you need more sophisticated monitoring, Bandwidth Vista will do that as well. You can, for example, monitor very detailed technical information about the current state of your TCP/IP connection. You can also view your history of bandwidth use, create alerts for when you exceed a total amount of Internet use, and change the program's opacity. The only problem I had with this program is that I couldn't get the screen to minimize. There is a setting that is supposed to allow the program to minimize, but it wouldn't work on my test machine.
That's the only shortcoming I could find. Other than that, Bandwidth Vista is an excellent tool.
Note: This program is donationware. It is free to try, but the author accepts and encourages donations towards further development.