Sysinternals Suite

The Sysinternals Troubleshooting Utilities have been rolled up into a single 'Suite' of tools. The Suite is a bundling of just some of the following: Sysinternals Utilities, AccessChk, AccessEnum, AdExplorer, AdRestore, Autologon, Autoruns, BgInfo, CacheSet, NewSid, NTFSInfo, PageDefrag, PsSuspend, RegDelNull, RegJump, Strings, Sync, TCPView, VolumeID, WhoIs, WinObj, ZoomIt, and more!

http://technet.microsoft.com/

System Explorer

This tool provides a glimpse into all you need to know about your system. Features include detailed information about processes, start-ups, explorer, IE add-ons, uninstallers, services, drivers, connections and opened files. There's even a way to check for suspicious files via VirusTotal.

http://systemexplorer.mistergroup.org/