Power supply voltage question

[Sase]

I've decided after seeing all those fancy cool cases on thinkgeek.com, etc. that I want to vamp up my ATX case a little. I happen to like LED's and their usage, and have put them in my car, etc. Upon stumbling across an LED distributer, I found something (fiber optic) called Lightning wire, which is sideglow cable. The only problem is I would like to make it so that it can connect to the PC's power source to make it work nicely http://www.sysopt.com/forum/smile.gif
What I need to know is what each pin is (voltage wise etc.) on the power connectors coming out of an ATX power supply so that I may connect it, or drop down the voltage to accomdate my little cosmetic change.

Let me know if anyone can tell me the information I need (I currently can't find my multimeter)

-Sase

[Bsdboy]

On a 4 pin connecter yellow is +12v
red is +5 and the blacks are ground.

Bsdboy

[captpete]

20 pin connector, 10 on each side. 1 and 11, beside each other at one end are 12v and 5v respectively. At the other end, 10 and 20 are both 3.3v.