what is best way to monitor IIS 6.0?

Question

monitoring can be include source ip, what is being served by iis, which work processor is being used, how much current load on IIS?

Answer 1

Performance counters will tell you about IIS load. Run perfmon.exe to see them.

And IIS produces logs that are by default under C:\inetpub\logs\LogFiles\W3SVC1 showing every single file served, including requester's IP address and more.