There are some very handy tools available at http://www.sysinternals.com/. They have a lot of amazing freeware to download. It’s unfortunate that the slickest freeware items available for download are not open sourced, but there is a lot of open source items as well.
Some of my faves:
- FileMon – monitors and displays file system activity on a system in real-time
- TCPView – a Windows program that will show you detailed listings of all TCP and UDP endpoints on your system, including the local and remote addresses and state of TCP connections. On Windows NT, 2000 and XP TCPView also reports the name of the process that owns the endpoint.
- Regmon – a Registry monitoring utility that will show you which applications are accessing your Registry, which keys they are accessing, and the Registry data that they are reading and writing – all in real-time
- Process Explorer – think Task Manager all "growed up", put on steroids, and cast away to the gym for ten years’ labor