he can't plug those directly into his speakers but he can plug it into his computer.  If you get to female ends you can plug directly into his speakers but loose the rear channel since you can only plug one of the 3 speaker cables to the ps3

for optical you will need a sound card that supports optical.  I wouldn;t bother with optical only if your going to be using a Reciver

The RCA to 3.5 that everyone's recommending would work find. But I think you'll only get 2.0...

For Video a use HDMI to DVI-D. Looks really clean an clear for me compared to when I use HDMI which just looks fucked up on my screen. Mine's a 25.5" 1920x1200 Samsung screen.

oh yes if your using a PC monitor make sure you set black level to Full

 This is what I was reffering to get stereo sound. I have used a similar set up at home when a friend brings a second PS3 since I only have two PC speakers. However, I'm still searching because you will only have stereo sound with this. You could use some "Y" connectors to spit it two the other speakers, but then you just have a lot of stereo speakers.

There isn;t really a way to get full 5.1 surround on LINE IN without doing audio through a reciver.  A fancy sound card might but thats something you have to look into

Agreed. I've been looking for a optical converter specific for the speakers he has. The HDMI is used for the video and the A/V only has stereo sound. There is an image here of that device, http://www.cnet.com.au/i/r/2004/Notebooks/Notebooks/creative_speaker_docking_cable_500x375.jpg, but it is made specific for that sound card. He needs this device with universal optical connector instead of a proprietary connector.

http://www.newegg.com/Product/Product.aspx?Item=N82E16829102021

If you have a spare $200 you can beef up your sound experience.

The speakers directly connect to the computer, the ps3 connects to the computer which will be played out on all the speakers (ALthough it will be just stereo with speaker fill). If you hook the ps3 directly up the the speakers, you will get 2/5 speakers working.

Optical is a digital signal and you would need some some of converter to put it to analog which defeats the purpose. I wouldn;t bother with optical unless your sound card supports it or your using a reciver

Squilliam said: http://www.newegg.com/Product/Product.aspx?Item=N82E16829102021 If you have a spare $200 you can beef up your sound experience.

Ha sort of expensive.  Id just stick with stereo and have your sound card software fill in the other speakers