Iquaba: Sorry for the delay. Never noticed the post!
the arduino connects to the PC via an xbee module. the serial data is sent wirelessly through the modules. The PC has an xbee connected to it via USB.
I have a vb.net program that can connect to the xbee via the virtual serial com port it uses. I simply read the data it detects on the given com port and then perform actions based on that. I can also send data to that same port, which in turn sends the data to the Arduino's xbee module. The Arduino sketch reads the data coming from that com port also and performs actions based on the data it reads from it.
Hope this explains it better. Let me know if you have other questions.
Andres