Get the ones I have! 400W THX certified, 4.1. They're logitech Z560. Cost me $200 at best buy about a year ago.
Now they have the new Z680 out, 5.1 and it's off the hook!!!
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3004879084&category=32861
lots of money but man what a system! (my Z560)