No friends yet.
home pc acting as a real server ? sounds strange - if your ip is not known to the rest of the internet world via name servers. just get a normal real server and these 'problems' will be non-existent.
I just re-read your original question - are you trying to host a live site using xampp? If so, don't. It's not secure, like, really really not secure. It's great for local development, but you shouldn't have xampp be publicly accessible.
Keep it internal and use the ip address, or use http://localhost/elgg