After looking for some time how to add IIS to Vista Ultimate I ran into troubles starting the server. Of course as soon as I found it on my own, I also found a detailed article .

"The process cannot access the file because it is being used by another process ..."

What do you know it was the truth. Skype has an option to use ports 80 and 443 under Tools->Options->Advanced->Connection. I unchecked it, restarted Skype and IIS went alive!