My advice is that you should get a multimedia setup only if you want a 2.0 or 2.1 system.
If you want 5.1 sound, multimedia speakers would not be a practical choice because the ones with Dolby/DTS decoders are so expensive that you would get better value from a setup with separate receiver & speakers.
Ok ang Xenon sa DVD player with internal Dolby/DTS decoders, but I think the WD's internal decoder does not decode to analog 5.1; it only downconverts to 2.0 in the digital domain, then decodes to analog 2.0.
A 5.1 digital signal can be passed through by the WD via toslink, but the output is still a 5.1 digital signal, not 6 separate analog channels.