My network speeds sometimes drop very low. Does a utility exist (either a built-in Windows utility like netstat, or a free 3rd party application) that will list in realtime all services on my system that are using bandwidth, and how much bandwidth they are using? I've found a couple (Axence Net Tools, Networx) that list all open connections, but they don't show me how much traffic is moving through each connection. I'm using Windows 7 Pro. Thanks in advance.

Check NetLimiter (shareware) or Process Explorer v.14.1 (show details for all processes / select columns / process network...)

Resource Moniter It's built into Windows 7 and does what you're asking.