Have look on ebay for 2nd hand altec lansing, I picked up a set of 5.1 for £5, original price was £150. Just had a look and thers some rather nice ACS340 on there new buy it now, ace speaker had them before my upgrade. Very loud with plenty of bass. Sub is very good quality nad heavy, tweaters very solid as well.
Also a set of ADA885, intersting 5.1 setup where the front centre is split between the left and right speakers, and when you dont want them in 5.1 mode you can slot the rears on top of the fronts.
http://www.simhq.com/simhq3/hardware.../altec_ada885/