Your local IP address (192.168.xxx.xxx) controls how the router routes information from the internet to the correct computer on your local network.  Your router gets an IP address from your ISP which is addressable over the internet.  This essentially puts your computers behind a hardware firewall and prevents someone on the internet from accessing your computer.  If you want your computer to have an IP address (and thus be accessible to anyone on the internet), disconnect it from the router and plug it directly into your broadband modem. 

Why would you want to do this?

Steve