any a/v geeks/pros here?

i got a 47" lg lcd tv a while back but it only seems to have a digital audio(optical) output. the tv has loads of inputs but i wanted to hook up some surround sound and cant do it b/c my surround system is only rca(analog) capable. is there a cheap adapter that anyone knows of that would work? ive been searching for a while now but i still havent found what i need. i did find one adapter but i converts the digital out to s/pdif and what im looking for is digital optical to rca..

:anyone: