Hooking an arduino up to a standard computer ( celeron )

I've had the idea of using an i3 celeron to handle more complex operations and issue orders and commands to arduino boards hooked up to it using serial ports, the question(s) are that how do you wire an arduino to one of those serial ports ( there's a bunch of small slots on each port ) and that if the arduino is hooked up to a serial port and the pc sends a serial value say like "A", will the arduino listening to the port interpret it exactly the same way as the pc wrote it?

Note - The other reason why I have a computer onboard the robot I'm working on is to handle video and audio streaming because I've heard from somewhere that the arduino doesn't have the processing power to handle video or audio ( I'll have to ask this one on a different forum like stackexchange )

Use USB. Otherwise, you're going to have to add serial line voltage converters. Who said it can't handle audio?

Wait - Doesn't the arduino already use the USB port for its power supply?

Is that a problem?

Not a major issue, I'll just rewire the power supply, but rather because there is kind of a tug-of-war situation with this because...

If I use serial port communication, it makes it easy for me to write the application to control the arduino on my pc because my pc already has built in libraries to handle serial ports and stuff

On the other hand, if I use USB, it would make it a lot harder to write the application for controlling it because I'm not exactly sure how you use a bus instead of an actual medium of communication to send instructions to an arduino

You're over-thinking this.

Hook your Arduino to your PC or laptop. How do you communicate with it?

How is that different talking to your i3?

Etcetera: if the arduino is hooked up to a serial port and the pc sends a serial value say like "A", will the arduino listening to the port interpret it exactly the same way as the pc wrote it?

No. You will have to write a sketch that runs on the Arduino and listens for incoming serial data and then does some action based on that data.

Etcetera: If I use serial port communication,

On the other hand, if I use USB,

The Arduino's USB port is just a USB-to-serial converter. So when connecting the Arduino to the PC via USB, the Arduino is speaking serial.

Note - The other reason why I have a computer onboard the robot I'm working on is to handle video and audio streaming because I've heard from somewhere that the arduino doesn't have the processing power to handle video or audio ( I'll have to ask this one on a different forum like stackexchange )

Possible arduino robot setup where the pc would not be needed.

http://www.lynxmotion.net/viewtopic.php?f=20&t=6343

Well that was a lot less complicated than expected…