localhost or actual domain?

Hello. I know this is slightly off topic but can someone tell me what happens when installing apache on windows and, instead of calling it 'localhost', I use the actual domain name instead? As the directions say can be done. Until today, on my local win98 machine, I have been using the name 'localhost' with php3 and mysql and could reach my online domain name and database as well as the local databases, etc... If I were to use my online domain name in a new local machine installation, how would the two domains get along? Would the local and the isp act as one domain? Or would they conflict? Can someone explain what goes on between the local and isp servers in this situation. Thanks.. Floyd Baker --