I had so much trouble making the xampp Apache run on port 80 on Windows 7.
“An attempt was made to access a socket in a way forbidden by its access permissions. : make_sock: could not bind to address 0.0.0.0:80 no listening sockets available, shutting down”
If are like me, has the problem, even after stopping the IIS Web Server, MS SQL Services, bypassing the Skype, that darn port is still in use by some other program. That port has been used by a system process with ID 4. I have googled so much and read so much hurdles to change IIS to listen on different IP and make Apache re-route the traffic to IIS & so on. I usually change the apache port to something other than 80. This is OK if you are using single WordPress. If you want to use WordPress Multisite, then you must not use any other port other than Port 80.
I accidentally find a solution to this problem. I was just looking through the Services and stopped one of them and voila, xampp ran successfully.
Start => Control Panel => Administrative Tools => Services.
In that list of Services, look for “Web Deployment Agent Service”. Just stop this. Now start your XAMPP. You do not need to stop the IIS, nor MS SQL Server services. However, you do need to stop any websites running in IIS using Port 80.
Now you can have your Apache and IIS running at the same time.