I've just had an "interesting" few days working with a new toy, a TEMPerLAN, from PCSensor.com. The TEMPerLAN connects to your LAN, and into the TEMPerLAN you also plug some 1-Wire temperature sensors.
I've now created a client program which runs on a Windows machine. It makes a wSocket connection to the TEMPerLAN at whatever IP address the PCSensor has been assigned, and via port 5200. The client software then sends just two bytes to the TEMPerLAN ($BB $82, as it happens.) This persuades it to send a simple string of data back to the client software, which interprets the string, and displays the temperatures the TEMPerLAN reported.
So why post this here? If you are looking to get started with Arduinos and TCP/IP, creating a TEMPerLAN clone might make an "amusing" project. My web-page gives much more detail, and the client software you can use to test your attempt to create a server in the Arduino. Note that this is a SIMPLE server, not a full blown WEB PAGE server. Along the way, novices might learn more than they know so far about TCP/IP.
I am new to it myself... apologies for errors in the tutorial... but the software DOES work!
Software and tutorial at...http://sheepdogguides.com/dt5n.htm
You don't have to be a Delphi programmer to benefit from the material there. You don't need Delphi to run the .exe which is included in the .zip.