Find out what process is slowing server...

We are having a problem with the process w3wp.exe, which is an IIS process. However, I need to know which app that is running under it is causing the problems. The process will cause the cpu percentage to jump from 30% to 100% and stay at 100% for about 2-5 mins, and this will occure about every 10-20 mins (we havent timed it).

We have an ideas on what is causing it, but not sure.

We thought it was PostgreSQL that was causing the problem, but i no longer believe that is the case, because i shut PostgreSQL down in the middle of the night when no-one was on the server and it still jumped the cpu usage.

Is there a way we can audit even which site is useing more cpu usage? or which files (possably: php, coldfusion, cgi, or IpSwitch [email server])?

This is getting quite annoying and short of sutting the sites down one by one and waiting, we do not know where to start.

Any help would be greatly appreciated,
-Nathan