BleepingComputer.com: Which rails do components draw power from

Hey everyone!

My physic teacher gave us an extra credit assignment that we can do on anything as long as it's a physics topic and it's "art" First off, he'll probably except this as "art" because he's interested in the topic of computers, and I think I'll call it "The Electrical Computer Collage"

Recently in physics, we've been doing electricity. We've been learning about voltages and amperages, so I figured this would be great for computers! So, I think I'll bring in some old parts and fire them up. I want to explain how the power supply has different rails with different voltages, and each has a specific amperage. So, after searching google, and not being able to find much of anything, I'm going to ask you guys: Which components use which rails? I know the graphics card and the processor use the +12V rail, and fans use the 5V (I think?), but that's about it. Also, what are the -#V rails for?

Thanks!

Is this of any help:
Power supply rail

There's some links at the bottom that may supply additional information.