vnStat is not available for Windows but there are a few alternatives that runs on Windows with similar functionality. The best Windows alternative is Cacti, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 10 alternatives to vnStat and three of them are available for Windows so hopefully you can find a suitable replacement. Other interesting Windows alternatives to vnStat are ntop (Free, Open Source) and SyWatchdog (Free, Open Source).
NTop is a hybrid layer 2 / layer 3 network monitor, that is by default it uses the layer 2 Media Access Control (MAC) addresses AND the layer 3 tcp/ip addresses. ntop is capable of associating the two, so that ip and non-ip traffic (e.g.