[Alyus]

Due to my inexperience I once considered buying PC speakers such as Logitech Z623 or the Klipsch Promedia 2.1. I would like to spend up to $500.00 USD for an audio set up for PC but would prefer to spend less since I am going to spend around $3,500 for computer monitor/hardware. 
 
I have come across the Audioengine A5+ for $399.99; will I need a sub-woofer for these? This is just a random product I came across on the web; please provide your suggestion.