Both mice delivered superb performances during the testing (with some deviations when glossy surfaces were used). Microsoft Comfort Optical Mouse 3000 falls into the average peripheral product category and it is recommended for an average user. Design and options have been seen before on mice (except magnifier option) and Microsoft should consider including more features with every new peripheral they design. Microsoft Wireless Notebook Optical Mouse 4000 on the other hand is sophisticated piece of hardware specifically designed for the mobile computing. Its price might be steep for some but you will know what you paid for when you test drive this beauty. Hardware Pacers wholeheartedly recommends this item for anyone who is looking into buying a portable mouse.