Sorry for bumping this old thread but I had an idea that I would like to share

You can write a Python script (Python has many libraries, including some MSN related). The script connects to the MSN network and acts as a translator for the Arduino

You have many options regarding the connection of Arduino and the PC. First one is the good old USB cable. You can also use the Ethernet shield (if you have a machine that's 24/7 and away, like a dedicated server or a VPS). You can also use BT, IR, WiFi.. There are MANY options, the only factor is knowledge and money ;D
I would like to see your progress (if you decide to build it!). I can also help
