The general rule for speakers is to buy from the same manufacturer for your 3 front speakers and 2-4 surrounds. For the subwoofer, look for the best performance.
I would be inclined to agree, that in your price range, an SVS or Hsu subwoofer will provide much more satisfaction and value [this is completely based on specs and reading other reviews]. The Axiom is only rated down to 28Hz Anechoic. The Hsu is rated down to 25Hz (STF-3 or VTF-1), and an SVS in that price range will go strongly to 20Hz and below. I own a Hsu and I've listened to an SVS cylinder. Both sound great for music, but for HT, SVS has the ability to go lower than a Hsu. Hsu is still a great sub though.
As far as my adivce goes, I think you'd be best served by getting 2 front speakers right now and slowing building your system. This will allow you to get much nicer speakers, and it will help you to take your time. Taking your time and listening to as many speakers as you can is very important. You don't want to regret a $1000 purchase.