just to let you know i'm in possession of a laptop with spdif output, till next week-end, but I don't have compatible speakers.
If it get some, I may be able to fix that bug, but I don't know nothing about spdif.
Is it the codec used by DVDs ?
How much is speakers' cost ?
In my experience, speakers are not specific s/pdif or not.
I set my soundcards driver (= ALSA) to "s/pdif output" (= Sony/Philips Digital InterFace). Then I connect my soundcards OUT (jack) with my Dolby Digital (=DD)/DTS Receiver's coacial s/pdif IN. That way the audio signal (multiple-channel/AC3/A52/IEC958/Dolby Digital or DTS or Stereo) is NOT decoded by my computer, nor by my soundcard, but it is digitally transfered to my Receiver. Then my receiver decodes it and passes the music to my 5 speakers. They are the same speakers that I have had for years, when only stereo existed.
So I don't know what you should spend on speakers, but what you DO need is a DD amplifier with a digital IN (= AC3 IN or: IEC958 IN or: s/pdif IN). A friend of mine had 5 little (computer) speakers from Creative that came with a s/pdif compatible sound card and a little amplifier (16 Watt) that could decode Dolby Digital via it's s/pdif IN.
My Digital Receiver costed about $220 (which is not much for a good Ampifier for in your living room).
I hope that this info helped you out. Maybe you can take the laptop to a friend or family's house who owns a DD Receiver? Good luck! If you've got any questions about spdif and speakers don't hestitate to ask.