anyone know how i can do this and make the sound come out of both stereo speakers, instead of just the mono signal that comes out of only one?

Don't you have a stereo out coming out of the computer, or a headphone jack?

Just go to Radio Shack & get a cable w/ a 1/8" stereo jack on one end, and 2 RCAs on the other.

oh shit. I think i must have a headphone jack. They look the same, no?

Yeah, or you can come out of where you plug your little computer speakers into.

My speakers have a headphone jack right on the front. You could even come out of this, but you're going to have to be careful w/ the volume.

I have a laptop, so there's only a headphone jack. That's what it's coming out of.