Over the years, mouse designers have become acutely aware of the ergonomic problems that heavy mouse use can cause. They've created a new generation of mice designed to fit the shape of the hand. These allow you to click the buttons with more natural movements.

There's no hard-and-fast rule here because hands come in an infinite variety of shapes and sizes. The important thing is to find a mouse that's comfortable for you. It should fit easily into the curve of your palm, and the buttons should be easy to reach and clickable without curling your finger.

Many manufacturers of highly-contoured mice make both right- and left-handed models. You're likely to find the right-handed version on the store shelf, but if you're a lefty and like the design, ask the retailer to order one for you, or you can call the manufacturer.

Just right for kids

If you have kids, you may want to consider a special kid-sized mouse or trackball. These tend to be heavy-duty (because kids are rough on anything they touch) and designed specifically for use by small, less-coordinated hands. Microsoft, Logitech and other manufacturers are beginning to turn out lines of mice and keyboards especially for young users. Even if you don't need a new mouse yourself, it's a good idea to stop by a computer retailer or check family-oriented computing magazines to see what's available.

It's hard to say how long any user-intensive gadget will stand up under a heavy workload, but with mice, quality generally follows price.

Choose a device that will last

You can pay anywhere from $15 to $120 for a mouse or trackball. Don't be seduced by the low end. Cheap, no-name mice are likely to break in a couple of months because the best way to make an inexpensive mouse is to skimp on the quality of the parts inside. If in doubt, just pick up the mouse. A good one will be considerably heavier than a cheap one.

Look for a replacement mouse from your manufacturer, or a third party mouse from a major supplier such as Microsoft, Logitech, Mouse Systems or Kensington. If you don't like what you see on your retailer's shelves, call up a manufacturer and ask for a catalog, or visit their home pages on the Web. Mouse makers produce more models than most stores are willing to stock, and the chances are good that you can find one you like with a little research.