You guys are missing the fact that he is limited to buying from only best buy.
**actually after checking some things..both of those subs are not too great. But the Martin Logan Dynomo 500 has great reviews and around the same price range. look it up.
"The Dynamo is a very good sub for small to medium sized rooms. It will play cleanly down to 25 Hz or lower given room gain. It is not an SPL monster but it is exceptionally good for music. I have had one for about 4 years now and it will remain with me. It is still one of the better subs I have had the pleasure of hearing solely for musical accuracy and I have had the pleasure of hearing quite a few. It is only 200 watts, not 200 watts nominal with a higher peak wattage, it is just 200 watts. It is actually a little surprising for HT use actually, it can hit with more impact than you would expect for it's size and specs."
-Review;
http://www.avsforum.com/avs-vb/showthread.php?t=1164000.
As for the Hz question..its really personal preference and how your system is setup. Some like the extra deep lows, some can don't.