You may want to consider one of these. The sub is only 34 lbs with 188 watts RMS. I think you will find it has way more omph than you need.

I just plug the sub into my headphone jack and use JBL speakers. You may also enjoy the satelites as many do, although I don't use mine.
http://www.amazon.com/exec/obidos/ASIN/B0002WPSBC/ref=nosim/coffeeresearch64672-20