Are you dead set on surround? On your budget I'd rather go for a decent 2.1 set unless you really plan to use the surrounds a lot for movies or games.
For 2.1 speakers, the most popular is probably the Logitech Z-2300, Amazon.com has them for $90.
The Swan M10 are getting favourable impressions, available at newegg for $100. Thread about them at hardforum with links to head-fi with more impressions.







