Special digital cable needed?


I just bougth a secondhand Yamaha DSP-E800 DD/DTS/Prologic decoder with built-in amps for centre and rear speakers. So I wanted to hook up my DVD-player, using a 75-ohm cable to feed the digital input on the Yamaha. Since the shop didn't have a digital cable and I didn't want to wait to play with my new toy, I just used an old analogue cable. And it works. And it sounds pretty good too. So my question is: will replacing this cable with a 75 ohm digital cable sound better? Or can I save the money and waste it on other joys of life?
satch
75 ohms characteristic impedance is beneficial, but not necessary. If you want to minimize jitter, then stick with 75 ohms and get a 1.5m length minimum. Ask someone with digital and transmission line experience for advice. Read this article I wrote on S/PDIF for more info:

http://www.positive-feedback.com/Issue14/spdif.htm
Thanks for the responses, untill funds allow I just use the old analogue cable. Audioengr, just one question: why a minimum of 1.5 meter? With analogue cable should be as short as possible, and 0.5 meter would be sufficient.
Satch - this article I wrote for Positive-feedback explains it:
http://www.positive-feedback.com/Issue14/spdif.htm
Thanx Steve, I read it and almost understood it - just let it digest for the night and I will be OK. Just for the record: I can lend a digital cable next week, and plug it in. I keep whatever sounds best......