Which w3wp.exe is the one I want?

If you have every tried to debug a web application running on Windows Server 2003 you will be faced with which w3wp.exe process do you attach to remotely. I have figured out a few ways. In order of ease:

1. User Name - If you change the App Pool Identity to something other than Network Service (like your personal user account... temporarily of course) you should be able to open Windows Task Manager and see name next to one of the w3wp.exe process. I highly recommend stopping and restarting the Application Pool (not just recycle it). The best part is you can also see the User Name in Visual Studio when are in the attach to process window and choosing the process.
2. CPU Time - If you open Windows Task Manager, now recycle the App pool. The CPU Time should go to zero. When you hit a page on the site, it should show some small value greater than zero depending on how much cpu the page actually takes. This will allow you to get the PID (you may have to add the column to Windows Task Manager) which you can see when you are in Visual Studio and attaching to the process.
3. You can also use Sysinternals (now Microsoft owns it so....) Process Explorer. Using this tool, you can right click on the w3wp.exe in its list of processes and look at the Command Line that was used to launch the process. The last parameter is the name of the App Pool. Assuming you are using different app pools for each web site, this will allow you to get the PID, and use that to attach to the process just like the other scenarios.

I hope this helps. I find it generally frustrating that it is so difficult to determine which process is the one I need. Oh well, this seems to work reasonably well.