yeh, you have to configure your router to forward port 80 to you router's IP address, then it should just work, if it doesn't there is a lione in the config file which specifies who can access the server, by default it is set to 80, which means eveyone using port 80, but it could have accidently been changed to something like 192.168.x.x (being your internal IP) which would stop external access, if it is that just change it back to 80 and it shoudl work
Lee