Welcome Rodge! As far as a sub overpowering your system you will have quite a bit of control over that aspect. The sub itself will have crossover and output controls, and your receiver might have separate controls for the LFE/sub output and crossover frequency as well. Also positioning a sub correctly in your room is crucial. I just received a pair of M3ti's I bought on eBay and WOW are they little performers! They are more than adequate for your room.
As far as the VP100, where do you have is set up? Is it above or below your TV? Are the speakers angled to the plane of your ears? If not try wedging a book or wedge-style doorstop under the front or back to point the VP100 directly at you. If the front of the speaker cabinet is behind the front of your TV try moving the speaker forward until flush with the front of the TV. Also if your receiver allows you to adjust the volume of your speakers individually I would look into picking up an SPL meter and adjust the speakers so the sound level is the same for each from your listening postition.
