How Do I link a C language Windows32 GUI application with my Arduino?

For some issues that exist( Ardulink doesn't work, Matlab costs money, etc.), I decided to build my own GUI with C language which I can. I was deciding to make a small car with DC motors and implement some buttons that say "UP", "DOWN" on the GUI that when pressed sends a signal to the Arduino and executes the command associated with it. But here's the problem.
How do I link my C program built in Code::Blocks to my Arduino??

If you mean link as in the c++ linker then you are a bit confused as you cannot link those programs together because they are on different hardware. Now if you mean "link" as in communicate between these two programs, that can be done.

The way to "link" it would be through the serial port. Make a GUI that sends serial commands to the arduino and make an arduino program that reads the commands and does whatever it should do. You can use any language you want for the GUI, all it needs to do is be able to open a serial connection and send bytes.

This Python GUI demo might give you some ideas. I think it will work on Windows if you give it the correct serial port definition.

...R

Thanks for the answers!
Thing is, tripphippie, I tried to make a program that sends info to a defined serial port, but it kinda failed, so I'm going to go with another GUI made in another language.