Digital Optical Cables - how important is brand?

I am presently using an Acoustic Research optical cable from my Pioneer Elite DVD/CD player into a Denon DTS receiver serving as a preamp with a Parasound 1000 HCA amp.

Maybe this is a dumb question, but are their truly significant differences in optical cables?
I do use DH lab Siversonic speaker wire with my RBH Sound speakers, and also a Tekline RCA connector from my receiver preamp outputs to my amp so I do think that decent cables are desirable, but the optical thing kind of throws me.

Any opinions are welcome and suggestions of a low cost (sub 50-75$) optical. That is if better ones than my 20$ Acoustic Reserach really do seem to make a difference.

Thanks.