The catch, of course, is that you really need to buy one in advance, keeping it on hand just in case of water damage. Still, if you're the accident-prone type, you might be better off spending $20 now than hundreds later to replace your device. Your thoughts?

Contributing Editor writes about business and consumer technology. Ask for help with your PC hassles at , or try the treasure trove of helpful folks in the . Sign up to have the e-mailed to you each week.