Windows Process Explorer is a free diagnostic utility developed by  Sysinternals, a Microsoft subsidiary.  It provides much more information than the standard Windows Task Manager, and can be downloaded from download.sysinternals.com/files/ProcessExplorer.zip, or run directly from live.sysinternals.com/procexp.exe.

This is part of the Sysinternals Suite of utilities including Process Monitor, etc.   These are generally for Windows Vista/Windows Server 2008 and later versions.