Imitating potentiometer

I'm trying to imitate a potentiometer so that I can control an RC car remote control using an Arduino.

What is the best way to imitate a potentiometer with an Arduino? Do I need one of these? http://en.wikipedia.org/wiki/Digital_potentiometer

Thanks!

Do I need one of these?

Basically yes.
You also need to make sure the voltage of what you are putting this in is less than or equal to the arduino and you need to connect the grounds together.

http://www.arduino.cc/en/Tutorial/SPIDigitalPot

The device runs on a 9V batter, but the voltage when I put a multimeter over the terminals of the potentiometer I get between 2.5 and 1.5 volts

Is there a digital potentiometer that only has 1 or 2 outputs instead of 6?

I get between 2.5 and 1.5 volts

It should be OK then.

Is there a digital potentiometer that only has 1 or 2 outputs instead of 6?

Yes there are lots of different types.
http://www.maxim-ic.com/products/digi_pot/

A great little "poor mans" digital pot woult be a simle DAC. (At least I think thats what you're asking :P)

http://www.play-hookey.com/analog/d2a_converter.html

A great little "poor mans" digital pot woult be a simle DAC.

No it would not be a simple DAC. It would only remotely be a DAC if the pot were connected between two rails.

Ah I thought he wanted to be able to vary the voltage? I guess I misunderstood the question.