Does your laptop spend more time on your desk than your lap? If so, you're probably causing your battery to wear out much sooner than it needs to.
See, it's a sad (and expensive) fact of life: You're lucky to get 18-24 months from a battery before it loses a good chunk of its charge capacity (meaning it no longer powers your laptop for as long as it used to).
And you're accelerating this unfortunate timeframe if you leave your laptop plugged in 24/7, which is common for most folks who work at a desk. Because the battery rarely (if ever) gets a chance to discharge, it loses its capacity to hold a charge.
The simple solution: Pull the battery out of the laptop and leave it out when you're deskbound. Most laptops can run on straight AC power, so there's no need for the battery. And it's easy enough to pop back in when you hit the road (though obviously you'll want to make sure it's charged, so plan ahead a bit).
It's a hassle, sure, but consider the price of a replacement battery: usually $100 or more. What's more, old, discarded batteries wreak havoc on landfills. Sooner or later, they'll leak acid into the ground. So it's in your best interests to keep your battery as long as possible, and to keep it from dying a premature death.