I want to make a fan controller using a potentiometer, what kind of potentiometer would I use if there are different kinds and would this work. ALso where would I put it, on the negative lead right? I know I sound like a n00b right now because Im just starting to get into electronics.

useful article
http://bit-tech.net/article/56/

Just what I was looking for hardnrg thx. also if I have like 4 fans on a bay bus could i take the bay bus lead and do it to that so I can control all of those fans on the bay bus.
Also I was wondering if I could hook a couple of LEDs to a battery and put it inside of the case. Would this work, or is it to risky with all of my parts in there.

you can hook up led's to a molex... you'll need to wire them up with resistors in series... use a led resistor calculator (google) to find out what values you need...

not sure exactly what you mean by a "bay bus lead"... but you'd need a potentiometer for each fan, and need to wire the fan+pot pairs in parallel...

Ok i understand now thx.