For multizone stuff, there has been quite a bit of discussion over on AVS and I follow it but dont do multizone myself so my be off the mark a bit....
You can of course use seperate PC's or devices like SLimMP3 units to decode at point but this is not elegant or easy to provide whole house single source...
You can use W..(another player) and a multichannel soundcard to decode to stereo pairs and then have 4 'zones' from one 8 channel soundcard... This is the same as above in that it is fine for multiple zones but not fine for all zones synced at once...
There was a beta player listed on AVS (have no link but could find it) that was designed for multizone but looked UGLY !! and beta !! I had a peek but ws put off by the looks...
I would say that if you are doing multizone and will need to purchase amps anyway why not get a multizone multi source amp... You can then use a player that maps to stereo pairs and have one input as primary.. This way you can have all on one setup or seperate source zones.. .Amps like
http://www.homecontrols.com/product.html?prodnum=KSKHS6440&comebackto=1 run a 6 source 4 room setup for sub 1400, not bad when you think about 4 stereo channels of amplification... Probably not want to put one in your main listening room but for whole house it would do... I have sen links of a RS232 controlled amp which would help tie it to the PC better but dont have it bookmarked...