Quickly determine which PID corresponds to which App Pool's w3wp.exe
This is a command that will quickly let you know which w3wp.exe you should be debugging on Server 2008 (IIS7, since the App Pool isn't listed in Visual Studio's 'attach to process' dialog). go to \Windows\System32\inetsrv and run "appcmd list wp" and you'll get a list that associates App Pool and PID