Thats the nice part about the Z-560's, they only have the blue light around the volume knob, no direct LED outwards. My wifes Z-340's, however, have that annoying power blue LED is does face directly outward and is freaking bright. Thankfully these computers are in our respective home offices so we don't get too much light in the bedroom.
As for turning off the speakers, I do that most of the time when not playing games. The reason is my apartment is VERY quiet due to super insulation and thick windows so ANY noise can be heard, this includes that almost inaudible hiss coming from my speakers. I can eliminate this hiss by using an actual sound card (like my SB live) but I prefer the crispness of the Soundstorm unboard audio, so I live with the very soft hiss.
-spike