Well you will need an amplifier or av receiver if you are going passive, tbh if you have the space get a pair of floorstanders, Bowers & Wilkins or Eltax id recommend, ebays good for cheaper stuff.
If you get active speakers, then all you will need is phono to 3.5mm jack from sub and speakers to sound cards sections (Center/Sub jack for Subwoofer, Green for stereo speakers) thatll be the most efficient way to do so.
But for overall clarity if you wanna put a few extra quid in, get an amplifier and some passive speakers. It will just sound better.
Truth be told if you get an Ok amplifier for around $100 and a pair of ok floorstanders for $200 you wont even need the subwoofer, unless you either have it really loud or want that higher tier quality of sound.