Skip the Axiom sub, and get a Hsu subwoofer. (www.hsuresearch.com)

I can almost guarantee that the next poster will tell you to skip the Axiom and get a SVS subwoofer. Both are very highly regarded. You can't do better for your money than either of them.

Hsu is coming out soon with some new models that have simply incredible prices. The new "STF" models. That may be your best bet.

Good luck and enjoy!