After my post on the Basic Arduino, I have had several questions on powering it. The Atmel chip requires regulated 5 volts so you can not hook it up directly to batteries and many wall plugs. Most of the time I use a LM7805 voltage regulator. They are cheap and easy to obtain. These regulators do run warm, so most projects require a heat sink. The input range of the LM7805 is 7 – 25 vdc. It is capable of 1.5a output.
The capacitors used in my circuit are 10uF and 1uF. Both of these values are very common in my shop and have worked well with my projects. The datasheet from the manufacturer uses .33uF and .1uF. The diode is not required but I like it for protection.