Front:
http://www.hometheaterhifi.com/volum...rs-6-2001.html
Rear:
http://www.audioshopper.com/sl6a.htm
Center:
http://www.audioreview.com/mfr/parad...7_2743crx.aspx
Sub:
http://ecoustics.epinions.com/Acoust...splay_~reviews
Honestly, I don't know too much about audio stuff as my dad's the audiophile of the family. But my surround sound speakers are basically a mish mash of all the older speakers he's owned but don't really use anymore, and they're just laying around. Right now he's running the Proac Response 2.5 for his hifi system, which actually sound amazing. I dunno how good they would be for surroundsound though, but I'm guessing they'd be pretty decent.
http://www.stereophile.com/floorloudspeakers/196proac/