Im not really a MS mouse/keyboard fan... I usually prefer Logitech.. I have enough MS products that I dont need their hardware too :D
But I have been playing around with a MS Cordless Optical Blue, and it seems nice.. But why in gods earth would you place a sleep button on the mouse!!!!!
Seems pointless!
EDIT:
I also like MS software for controlling the mouse.. But it does use more resources then Logitech :(
