Hello everybody I'm very new to the arduino.
I've been wondering; When I connect a potentiometer to an analog input of my arduino, does it make any difference what size (as in ohms) I use? AFAIK the arduino will always read values in the range 0-1023, no matter the size of the potentiometer.
ps: I've been searching the forum before.
You can use any size as it simply splits the voltage.
However, if you use a very small one you will draw lots of current, if you use a very large on there will be a high impedance on the analogue input and so it will be more likely to pick up noise.
Therefore, like the three bares, use a medium size one anything between 1K and 100K will be fine.
Thanks a lot for clarifying. I have no problem with the whole software part of the arduino, but I am a complete noob when it comes to the whole electronics part. I guess I better try to find me a copy of the getting started with electronics and start reading. 
As Mike says, pots between 1k and 100k will work, but best to use 10k or 20k pots. The datasheet indicates that accuracy will be lost for values higher than 20k.