OK don't worry about the power led.

Put the cables as seen in the above post, have all the labels on the cables facing the bottom of the case, except the speaker turn it the other way. It is fairly easy.

If you cant manage to do that leave all the other cables and just concentrate on the power sw , you know what pins to put them in so trial and error to see which way around to put it at.

Download Spybot

Revmoves Spyware and other poo that could be causing it to happen.

And for the Power Led:

Here is the section we need.

The rest of the manual can be downloaded here:

http://europe.giga-byte.com/FileList/Manual/motherboard_manual_ga-p35-(d)s3l_2.0_e.pdf

Also...

Is it a store brand computer? (dell, hp, compaq, ect) If so what model?

Usually they are both labeled on the mobo and the cable, on the mobo it will say Power Sw - for the power button cable labeled Power Sw put that in the place of the two pins usually the label on the cable facing you.