I dampen a soft cotton towel with some Windex, works great for me.
I use a brillo pad....really makes it shine (that was a JOKE !! :roll: )
Seriously, I thought windex could ruin LCD flat panels by making them foggy...perhaps the Z has a hard cover over the screen?...but I would generally never recommend anything besides a superfine camera lens cloth and plain water (and only water if absolutely necessary.)
I agree with the idea of moisten the cloth only, never the Z directly...it may work fine 99.9999% of the time, but when you get water in the electronics just once...say bye bye to your $$.