Process Explorer (http://www.sysinternals.com/ntw2k/freeware/procexp.shtml) 9.0 is a free Windows taskmanager replacement, showing you all kind of information on which handles and DLLs processes have opened or loaded. The best: it's free! I've been using it since V8.0 and can recommend it to every Windows user.

Process Explorer works on Windows 9x/Me, Windows NT 4.0, Windows 2000, Windows XP, Server 2003, and 64-bit versions of Windows for x64 processors.