LanSpeed2

LanSpeed2 is a very simple Windows utility that helps you monitor network traffic, relying on a very user friendly approach to serve its purpose.
The application is indeed pretty easy to use although it's supposed to target more experienced users in need of keeping an eye on network data.
The interface mostly comes down to a few gridlines that can be placed anywhere on the screen and showing LAN traffic in real time.
Additionally, the main window, if it can really be named so, shows the current, maximum, average, total today and total session download and upload statistics.
The interface is fully customizable though, so you can always right click the icon placed in the System Tray and set drawstyle, transparency, number of gridlines, update speed, colors and number of bars and points.
In case you're using multiple adapters, LanSpeed2 lets you pick the one you wish to monitor, so it's also recommended to have a look in the settings menu before anything else.
While LanSpeed2 runs on low resources and doesn't hamper system performance by any means, it doesn't work on Windows 7 and Vista. It runs okay on Windows XP though, so it's most likely just a compatibility issue.
Overall, LanSpeed2 can come in handy to many of you, especially because it provides network statistics in such a simple way. Still, Windows 7 compatibility is a must have nowadays, along with more customization options, including skins, to allow users change the way the app looks a bit easier.