You are going to want to either have powered speakers or a receiver/amp.  The Edifiers look like a great powered speaker option, but I have also been looking for the right receiver/amp for this.  I have a 5.1 receiver with multi-channel input which I may move over to my PC and get a new one for my main audio system, but have not decided for sure yet.  Eiter way, if you get a reciever be sure it has multi-channel input supporting 7.1.
 
Please report back on what you end up getting.
 
Did you get a sub to work that is plugged into your CSUB port?  If so, I'd love to hear how you connected it, and what you used to verify function.  I have not gotten mine to work from that port yet.

but I must say that I have the most complicated Reciever, so it could be on my end