How does one transfer data from a c# program to an arduino module via the internet?

Could someone throw me a link or two to a tutorial or article that could assist one in learning how to transfer data from a c# program (using windows api) to an arduino module over the internet? I've found some tutorials on controlling the arduino through a web browser but nothing that shows how to do data transfer from a c# program.

Have you got an Ethernet shield on your Arduino ?
Yes. I am using an arduino uno module and the arduino ethernet shield. I am using a wgt624 netgear router and some cat5 cables to connect the shield to the router to the pc.
You could do it with web protocols, but personally, I think its just a question of establishing a UDP socket connection between the two devices. The Arduino end is handled here. The C# end is pretty well described in this article