Question about 5.1 surround and PS3

[Makall]

I bought the Logitech X-540.

Theres this green/orange/black cable that comes with it. The green one is front, orange is middle and black is rear.

It comes with a splitter that splits the green in to a red and white jacks. Well, I can use the AV cables that came with the PS3 and plug it in to the red and white jacks from the split green cable.

Sound comes through, but I'm just wondering if it's considered 5.1 surround sound? Because the orange and black cables that does mid and rear aren't used?

Thanks.