localhost is an alias for the tcp loopback address 127.0.0.1
If you are saying http://192.168.0.3 doesn't work in your browser, check for any firewall software on your computer or the web server that might be blocking access.
192.168.x.x are "non-routable" ip addresses for internal LAN's, addresses in this range are not accessible from the Internet.
It appears your router address is 192.168.0.2 The addresses you listed should work as long as your router does dns forwarding.
If your problem is accessing your website from another location, perhaps you haven't forwarded external traffic on port 80 to your webserver's LAN ip. This is something you do in the router configuration and setup.
One last potential problem from the "outside" is that many cable/dsl ISP's are blocking port 80 so you can't run an external webserver on their broadband bandwidth.