When i purchased speakers for my Home Theater on a budget i decided NOT to get a subwoofer and chose bigger floor standing speakers for my fronts. I knew eventually i would want a subwoofer but at the time i was content with the bass that my fronts provided. I now want to add a sub to my HT but i want to be sure that what i get will actually provide a noticable difference in my setup. Right now this is what i have: JBL N38II fronts JBL Ncenter center JBL N26II surrounds Onkyo TX-SR600 receiver When it comes to subwoofers i am pretty much ignorant. Right now i use my HT mostly for DVDs and Xbox. What would be a good subwoofer choice under $500 that would compliment my setup well. I would be willing to spend a little more IF it would provide a significant performance increase. Any help that could be provided would be very appreciated. Thanks!