I just bought a logitech Z-680 last Saturday and honestly, I'm more than satisfied. They have a promo and it includes a wingman steering wheel with force feed backup. What I like more about it is it has it's own Dolb Digital, DTS and THX built-in decoder. Even if I'm using the very cheap CMI sound card, the sound is still great and it has a very nice deep base. I'm planning to purchase just the SB live sound card to make it sound better.
I would highly recommend this to any body.