Yes, you need a receiver or something along the lines of an integrated amp (preamp and amp but no processing). Something as simple as this Dayton Audio DTA-100a Class-T Digital Amplifier 50 WPC Provides Power To Computer Speakers, Bookshelf Speakers, Headphones, And More! 300-383
I guess it also depends on what type of output you have from the computer - maybe something like one of the digital amps at Parts Express that have USB input might work as well.
When you say "gauge" wire, you mean a harness with a special connector to connect the cubes to the bass module I presume? That one you may be hosed on because unless it is a common connector, you will have to get it from them or find one online. Their crossover is in the bass module, so you ideally want to go that way, otherwise you need an A/V receiver that has the ability to manage the crossover. Integrated amps and most stereo receivers won't have this.