I would hate to disagree with my learned colleagues....but.
It is possible to put together a decent 5.1 speaker system for $500. Simplest is the Hsu performance package 1, a 6.1 system with an 8" powered subwoofer for $500.
Mission and Mordaunt Short both make 5.0 systems for around $250 available from TSTO. Match them with any modest sub from the excellent sub manufactures like Hsu @ $254, AV123 @ $200 and have a very nice 5.1 system. If you cruise eBay, folks hereabouts have picked up the BIC 12" sub for $250 delivered.
The Infinity Primus 5.0 package can be found for around $250. Mix with $250 sub and add music. These systems won't flex the walls playing WOTW but will sound plenty good IMHO.
Right now is a good time to find heavy discounts because of Christmas and the newer models coming out. Gotta get rid of last years stuff.
Go shopping, be happy.