Not sure which I should get in the future. The MX is rechargeable, has side wheel, and automatically switches from precision scrolling to hyper-fast. On the other hand, the VX has a zoom slider (which I heard in an Amazon review can be programmed to do almost anything), is cheaper, and when the center button is clicked, it functions as a center click. I'm leaning towards the VX, mainly for the center click (which I love and use all the time when I'm on the internet). I've just got a couple of questions regarding assigning buttons different tasks. 1. Should I use Logitech software, USB overdrive, or Steermouse? 2. Can the search button on the mouse be assigned to perform a keystroke (such as Expose, Spaces, Dashboard, etc.)? 3. Was the Amazon review I mentioned earlier correct in that the zoom slider and the forward/back buttons on the VX be programmed to perform almost any task? 4. Can the buttons (on either mouse) be programmed for different tasks depending on the application? 5. Does the VX have a manual power button to turn it off, or do you have to put in the USB receiver? I think that's all the questions I have. Thanks in advance for the help.