I use my PC speaker system to listen to MP3s while working and when I have the time, when gaming. Age of Empires II never sounded so good! :)
I really enjoy this system, and I will definitely buy Boston speakers again (if needed - I plan on keeping this system as long as possible).
I personally don't want to watch DVDs so 4.1 sound works perfectly for me.
Note: You need two audio inputs for these speakers to work properly. Or you can buy an adapter for your machine.