Finally, I got my Windows Live Writer working again on my laptop. Windows Live Writer definitely my favorite blogging tool. :)
I built a Set State callout for my client recently, what I have learned during development was that before setting state of the activity record. It will automatically call the CRM web service to set the Actual End Date of the activity before setting the status. So this means there's two web service calls in the background for changing the state of any activities.