If Task Manager Extension is Task Manager on steroids, then Mark Russinovich's Process Explorer is Task Manager in a ripped anabolic fury, fueled by high octane rage. In other words, it's extreme:

Although it can be a little overwhelming-- I think it just kicked sand in my face-- it does have some features that I prefer over Task Manager Extension, namely:

• A menu item to enable/disable replacing Task Manager
• Drag and drop spy icon button to visually identify windows and their corresponding processes
• Real-time, color-coded highlighting of changes
• Native support of .NET processes
• Shows TCP/IP connections for a given process
• Lists all strings found in a given process

.. among many, many other things. And of course it duplicates all the functionality of Task Manager Extension. If you've outgrown Task Manager completely, this is definitely the tool for you.