Finding which programs access the internet

[mrthingtome]

I've recently been experimenting with packet sniffing for educational reasons, and have noticed that my computer is communicating via UDP constantly with at least two servers I don't recognize. I suspect that I may have some unwanted software hanging around, and I wonder if any of you know of any way to find out what programs are accessing the internet unbeknownst to me.

Any ideas?

[PlausiblyDamp]

http://www.microsoft.com/technet/sysinternals/Networking/TcpView.mspx is a good tool for this, and it's free!

[mrthingtome]

Perfect. Thank you very much.