Hello everybody.
I am planning on making a 4 legged robot, using this as base: http://www.robotshop.com/dagu-quad-bot-quadruped-walking-robot-2.html . But there is no microcontroller or servo controller included. Now what I would like to know if it's enough to only have an arduino board to control those 4 servo's or do I also need some sort of servo controller?
Thanks.
That walking robot uses three servos per leg for a total of 12 servos.
Per http://arduino.cc/it/Reference/Servo:
The Servo library supports up to 12 motors on most Arduino boards and 48 on the Arduino Mega.
In other words, no, you would not require a servo controller.
The Dagu quadbot uses only 2 DOF legs, so 8 servos in total. Absolutely no problem to control 8 servos with an Arduino Uno. Just make sure your battery is strong enough to power 8 servos.
Thanks to you both. That was all that I needed to know. 
Depending on the level of control desired for the servos, it may be worth while to employ a stand alone servo controller. Actual experimentation with the arduino and the servos will provide the info you will need to make a decision.
Bajdi:
The Dagu quadbot uses only 2 DOF legs, so 8 servos in total. Absolutely no problem to control 8 servos with an Arduino Uno. Just make sure your battery is strong enough to power 8 servos.
The maximum voltage is 6V per servo. Would a rechargeable 6v battery do? I heard something about the voltage dropping when the battery gets decharged. Is there something that can be done about that or is that no problem?
I heard something about the voltage dropping when the battery gets decharged.
Well, duh.
Is there something that can be done about that
Don't use the battery.
or is that no problem?
I generally think of dead batteries as a problem. Your mileage may vary.