Go to Radio Shack, show them the battery, and pay about $4 for a new one. Make sure you get the same battery though, if you don't it will do damage.
I just recently had to replace the battery on my old gateway. It's about 3+ years old. You don't need to really be concerned about it for atleast 2 years. And sometimes it will be much longer then this. One thing you might want to purchase is a multimeter (voltmeter). It will give you a reading on your battery and tell you if it's dead or not, or how much juice is left in it.
Originally posted by: Baked
You take the battery to radio shack and get a new one. They last real long as long as you have the system plugged in. I haven't changed my bios battery for a couple years.
I've always refered to them as cmos batteries. Am I wrong?