Another perspective. Nothing against what everyone else is saying, but IMHO, use the unit for a month or so before deciding on a mouse. I know there's a certain comfort-zone factor in involving the entire arm in the computing process. But, give yourself a little time to navigate the learning curve with the trackpoint and touchpad. You'll be surpassed how quickly you become proficient. I used the mouse for years with my Toshiba and Dell notebooks. But I couldn't decide on a new mouse when I got my ThinkPad early this month. And after a few weeks of being mouse-free, frankly, I don't miss it. IBM's touchpad is much more responsive and the trackpoint is larger and more comfortable than Dell's or Toshiba's. You'll get really good at using them, very fast.
A mouse is just another thing to carry. And you still need a surface to use it on. The joy of the ThinkPad is that it is small lightweight and self contained. You grab it and go. Why load it down with add-ons? It's a new toy. Learn to use it in new ways. As I said, just another perspective....
