Well, I've tested the speakers out
Connected them up downstairs to a Sony CD player using the optical lead.
Speakers are very well weighted, which is always a good sign of quality, and the sub...woh...people are right in saying, you don't know how big it is until you get it out of the box!
Played a bit of trance/classical/rock, and was pleasantly surprised, when set to Pro Logic 2 Music.
Bass on the Sony CD player wasnt as good though I don't think, because even when the bass was on full on the system, the bass wasn't mind blowingly loud, but very warm and natural sounding (I also put the sub in the middle of the room, so it wasn't in the best of places)
I'm guessing when connected to the PC, it'll be louder and more fulfilling!