Great system for a true budget price. I also think you should keep the floorstanding towers for the front - they will help fill in the mid-bass (between the subwoofer crossover frequency and the lowest frequencies that your other speakers can produce - like 80Hz to 150Hz) much better than the bookshelf speakers could.
Keep your eye on Craigslist and you might be able to "upgrade" that sub (sell the Sony) if you find a good used Velodyne, JBL, etc with a bigger woofer and more power.
Well done - how does it sound?
2-Ch (HT L/R): Oppo BDP-105 BD, Adcom GFP-750 pre, Bryston 10B Sub Xover, Bryston 4BSST2 / Paradigm Signature S4 v.2 (L/R), (2) SVS SB12-NSD (Subs)
Home Theater: Bryston 4BSST2 amp / Paradigm CC-590 (C), Outlaw 7700 amp / (4) Def Tech UIW-RSSII (LS/RS/LB/RB), Samsung 46” 3D LCD