Only one usage of each socket address (protocol/network address/port) is normally permitted. : make_sock: could not bind to address 0.0.0.0:80

This is my first time trying to install an Apache server on my Windows XP machine. Previously I was using IIS. I installed Apache 2.2 and was using the self installation program provided by Apache.

Upon installing Apache, I immediately received the following errors;

The Apache service named  reported the following error:
(OS 10048)Only one usage of each socket address 
(protocol/network address/port) is normally permitted.  
: make_sock: could not bind to address 0.0.0.0:80     .

It seems that the error was saying that there was a conflict in using the port 80. My natural response was to stop my windows firewall. However, it did not work. I was finally able to figure out the issue and it was because I was still running IIS on my Windows machine and therefore there was a conflict between Apache and IIS server.

I uninstalled IIS and I can immediately start Apache server with no problems.