One Thumb Down. Product/Link: Microsoft® Trackball Optical Synopsis: Multifunctional optical mouse ball. Requirements: Win9x/Me/NT® 4.0 with Service Pack 5+/2000/XP Home Edition or Professional, 25MB disk space, 16-32MB available RAM, Internet Explorer 4.01 with Service Pack 2+, PS/2 or USB port, 486DX 66 MHz+. For Mac: Mac OS 8.6 to 9.x, Mac OS 10.1 to 10.3 (excluding Mac OS X), 15 MB of available hard-disk space, an available USB port. Price: USD34.95. Rating: A mouse is your best friend. Comment: After 16 years of pushing mice around, Tad developed "computer elbow." It's like tennis elbow for chair potatoes. A physiatrist recommended a trackball to reduce arm movements while the primary physician suggested a skateboarder's elbow guard to prevent further injury from excessive leaning - such as at bars. Unlike the traditional two-button trackball operated with a couple of fingers, the Trackball Optical has four customizable buttons, a customizable wheel, and a ball worked by the thumb. Except for the ball it's very similar to the very versatile Microsoft IntelliMouse Optical which Tad normally uses, primarily because it doesn't need to be disassembled and cleaned weekly. But, and here's the real rub, Tad's been using a regulation mouse too long. He kept trying to move the trackball base instead of using the ball. Won't work. Other problems included lack of precision when working with graphics. The ol' thumb just ain't that accurate. Tad's hand is too large for the admittedly substantial unit (6-½" long by 4" wide). Body parts didn't fall where they should. Also, it takes four fingers to operate efficiently; using the ring finger to do anything other than display a ring isn't natural. Lastly, after two days Tad's thumb started to hurt. So now we have a sore elbow and a sore thumb. Conclusions: If you suffer from too much mousing about, start boning up on shortcut keys; if you're an old dog, forget new tricks.