PS3 & 5.1 surround sound, yo. (help plz)

'lo. I've returned with a new issue. ;P

Going to be blowing this month's earnings on a HDTV and PS3, but I've had the seed planted in my mind that I can get 5.1 surround sound on my PS3. I'm now wondering... how.

My speakers are some £30 SPKRKIT559 things which came with my DVD player. They use RCA input (http://www.zpluscable.com/images/pro...eo-rca-end.jpg) which doesn't seem to be too common anymore.

I've done some reading and established that I either need HDMI or optical I/O for connecting speakers directly to the PS3. So... my question is... can I use a decoder/converter with either the LCD TV or PS3? I don't know of any, but I'm sure one exists.

Thanks in advance.