That means that Apache is trying to use a port that the system is already using. Go to the cmd promt and type 'netstat -a' and look for what is using port 80. Go to your http.conf and go to line 268 and change the '80' to say, 85. I don't think that anything else uses port 80 by default (I could be wrong). If something else is using port 80, let me know what it is for future reference.
--Rich