A co-worker posted a how-to using IIS Debug Diag.  After going through this process, I have a new found respect for how easy and straight forward using IIS Debug Diag is

http://blogs.orcsweb.com/jeff/archive/2008/05/29/using-iis-debug-diagnostics-to-troubleshoot-worker-process-cpu-usage-in-ii6.aspx

Tess posted a similar blog recently discussing which tool to use when.  It's a good read.

http://blogs.msdn.com/tess/archive/2008/05/21/debugdiag-1-1-or-windbg-which-one-should-i-use-and-how-do-i-gather-memory-dumps.aspx

Enjoy!

Steve