I recently started my home theater/audio system. I currently have the Harman Kardon AVR-310 receiver and AR S50 mains. My next addition will be a subwoofer. I am a college student on a limited budget who lives in a smallish dorm room. Budget: looking to spend up to $300 or so Room size: about 12'x12' I have a subwoofer for my computer speakers (Altec Lansing ADA-885) which is 60 watts. That thing puts out quite a bit of bass. It can shake the walls pretty good if I turn the volume up. (these speakers are great for the price, btw, $200) I am looking for recommendations for a subwoofer (and place to buy it) that fits these general qualifications (up to $300 or so, 12'x12' room). Any help would be greatly appreciated.