If you are using Windows 8 or Windows Server 2012, and Apache service won't run (you have something like make_sock: could not bind to address 0.0.0.0:80 immediately after installation) what means that something occupies port 80, which is Apache is trying to use. You can use Tcpview tool to see what occupies port 80. Then I did that I saw that is was a process called "System". While "System" can actually refer to many system services, it seems that there are two common cases present:
1) Web Development Agent Service (MsDepSvc);
2) World Wide Web Publishing Service (W3SVC).
If disabling any of these servies does not help you can use some other tools to dig deeper in your quest of finding service responsible for port 80.
P.S. There is of course other solutions to that, most simple of which is changing port to which Apache will be listening.
