Well that indicates you have something running on port 80, which you already know
What windows version are you using.
Look in services for any of the following:
W3SVC,(world wide web publishing service), MSFTPSVC, the IISAdmin service. Stop any that you see
Do you have under services and applications a Internet Information Services? If so stop it too
Alternatively download this tool.
(download the free version at the bottom)
Run it with conjuction as it says, it will tell you which service is running on port 80, then you can stop it.