Now I've been looking at these two speakers and i m not sure if i should go with the affordable 5.1 set or the more expensive 4.1 set. I have enough money for the z560s and i m just wondering if they are worth the extra money. They are alot higher power(about 200watts RMS that 400 RMS is BS) but there were some reliability problems with these. Now with the alot more affordable z640s i have heard of no reliability problems but they are not as high powered as the z560s and they have tiny 2' drivers in the satelites which is a major turn down for me so if anyone who has a set of either of these please give me a hand in my decision. Thanx alot.