Multiple connections for one NIC

Is there some what to create multiple networking connections from one networking device?
I have my router secured, but I don't want to have to go through the hassel of re-entering the IP, gateway, DNS, ect. each time I come back from a LAN.
Oh, and I'm running Win XP Pro

>>3
DHCP is a protocol for clients to automatically receive TCP/IP configuration (IP, subnet mask, DNS) from a DHCP server in a network. If you have a DHCP server (hint: most routers, all wireless access points, etc.) at every place and set your TCP/IP configuration in Windows to "Obtain an address automatically" or whatever it's called in English, and enable the DHCP client service in services.msc, you'll be able to move anywhere with a DHCP server without worrying about configuration.