Serial Read - Program To Display Position In A Textbox?

I'm working on a project that incorporates an Arduino Duemilanove board and a program that a wrote in VB 2008. Basically, when the Arduino receives a symbol from COM3, it sets a Pin on the board, high or low. I'm using two Pins, one is going to be for a laser, the other a relay. The relay is going to close a circuit, and act as the button on the Nerf Vulcan. That's right, I'm creating a Nerf sentry gun.It's going to be fully controlled from my computer. I have all of the code done for the servo, and all of that, both on the Arduino and in VB.

The Arduino sends the angle of the Servo that will control the right and left movement of the gun through COM3, every time it changes. I want my program to display that position in a textbox, as my program needs that value in order to properly function. Basically, I need the code to read from the serial port, and display what it receives in a textbox, textbox3.