This thing eats AAA batteries like crazy. Also, sometimes difficult to awaken. I replaced mine with the larger Logitech BT mouse, and have been very happy with that. Using on a Dell D610.

the logitech v270 should be cheaper too (it was $30 from buy.com when i bought it 2 months ago). i'm also using it with a d610. there's a little bit of a delay when the mouse is inactive for a while, but you get used to it. still on the original set of AAs, which were included.