The scroll wheel sits between the two main buttons and moves from side to side as well as up and down, with one minor tactile difference between the two scroll modes: horizontal scrolling with the dial makes a tangible click as each page moves, but up and down scrolling is completely smooth, with no tactile feedback. We prefer the ratcheting feel of a click wheel for scrolling through individual pages (featured in other mice, including the Logitech MX Revolution). The smooth dial that Microsoft incorporates into its mice feels sludgy and awkward. The scroll button itself is preset to activate the new Windows Vista Flip 3D overlay where you can quickly view all of your open windows in a digitally organized stack. And as with most mice, you can reassign all the buttons with the Intellipoint software.
The technical highlight of the 4000 is a proprietary technology that Microsoft calls Bluetrack, which combines the precision of laser tracking with the wide coverage of a standard optical mouse to let you use it on virtually any surface. This versatility should come as a relief for jet-setters who don't want to lug a mouse pad around with their hardware; now they can mouse on a variety of tabletops, carpets, and other rough or reflective textures. While these surfaces present a problem for traditional mice, the 4000 scrolls beautifully across all of them. The one exception we found is glass. In that case, the cursor became erratic, moving very slowly at times and jumping across the page at others.
At just 4.04 inches long and 2.39 inches wide, the Microsoft Wireless Mobile Mouse 4000's small footprint tucks easily into a laptop case or a bag compartment. The wireless transceiver can supposedly deliver an uninterrupted connection up to 30 feet away, and the promise of cable-free trips is definitely a plus for mobile professionals and traveling Web surfers.
