content: I've had the Expert Mouse for a couple years. It works great on Windows XP, and the hardware is reliable and easy to maintain (especially cleaning is very easy.) However, the drivers for this trackball are not supported under Windows Vista, and Kensington's support department will tell you that they never will be - if they ever respond to your support request. And, both the Expert Mouse and Vista are current products! This means that on Vista, you can't use the two top buttons, or any of the chording (double-presses) that Kensington advertises, and that I bought the Expert Mouse for. The arrogance of Kensington is unbelievable. You really can't count on them to be there for you when you need them. It's like they're *trying* to go out of business. Avoid this product.