If your TV or cable box has red/white audio outputs - you can use a stereo soundbar from Zvox or other companies in the next room. But this will only give you stereo. (Best Buy has a selection of these)
HDTV soundtracks are really 5.1 just like a DVD player. So you really would want a 5.1 speaker system and a long optical cable.
You can get long optical cables from
www.monoprice.comThere are some nice Logitech computer speakers that are 5.1 and take an optical input for about $250. The soundbars are nice - but real 5.1 soundbars run $500-$900.
http://www.repaircable.com