Free Process Viewer [Advanced Task Manager]

Process Hacker is a feature-packed tool for manipulating processes and services on your computer.
Key features of Process Hacker:
* A simple, customizable tree view with highlighting showing you the processes running on your computer.
* Detailed performance graphs.
* A complete list of services and full control over them (start, stop, pause, resume and delete).
* A list of network connections.
* Comprehensive information for all processes: full process performance history, thread listing and stacks with dbghelp symbols, token information, module and mapped file information, virtual memory map, environment variables, handles, ...
* Full control over all processes, even processes protected by rootkits or security software. Its kernel-mode driver has unique abilities which allows it to terminate, suspend and resume all processes and threads, including software like IceSword, avast! anti-virus, AVG Antivirus, COMODO Internet Security, etc. (just to name a few).
Find hidden processes and terminate them. Process Hacker detects processes hidden by simple rootkits such as Hacker Defender and FU.
* Easy DLL injection and unloading - simply right-click a process and select "Inject DLL" to inject and right-click a module and select "Unload" to unload! & more...

Process Explorer, Ever wondered which program has a particular file or directory open? Now you can find out. Process Explorer shows you information about which handles and DLLs processes have opened or loaded.
The Process Explorer display consists of two sub-windows. The top window always shows a list of the currently active processes, including the names of their owning accounts, whereas the information displayed in the bottom window depends on the mode that Process Explorer is in: if it is in handle mode you'll see the handles that the process selected in the top window has opened; if Process Explorer is in DLL mode you'll see the DLLs and memory-mapped files that the process has loaded. Process Explorer also has a powerful search capability that will quickly show you which processes have particular handles opened or DLLs loaded.
The unique capabilities of Process Explorer make it useful for tracking down DLL-version problems or handle leaks, and provide insight into the way Windows and applications work.

Personally i like this one more out of them all, i use it instead of the normal task manager

System Explorer is free, awards winning software for exploration and management of System Internals. This small software includes many usefull tools which help you Keep Your System Under Control. With System Explorer You get also fast access to File Database which help you to determine unwanted processes or threats. System Explorer is translated into 21 languages and is available for download in installer and portable version.
* Detailed information about Tasks, Processes, Modules, Startups, IE Addons, Uninstallers, Windows, Services, Drivers, Connections and Opened Files.
* Easy check of suspicious files via VirusTotal, Jotti service or our File Database.
* Easy monitoring of processes activities and System changes.
* Usage graphs of important System resources.
* Tray Hint with detailed System and Battery status
* WMI Browser and System Additional Info
* Multilanguage Support

AnVir Task Manager is a tool that controls everything running on computer and provides Windows enhancements that help in every-day work
Monitor processes, services, startup programs; replace Task Manager
Get rid of spyware and viruses that your antivirus missed
Enhance and tune up XP or Vista
Speed up your PC and Windows startup

This is more than just a task manager, even in the free version there is a host of extras, i did not explore all of them, you can even delay programs that run on start up, so they start after the main system has booted, making it faster