400 charges? Is that all I get?

I've been somewhat without a computer this week. OK, that's not really true since I'm typing on it right now, but it's been more difficult to use. Suddenly the other day I went to turn it on and it wouldn't start up, so I figured it was out of battery. I charged it overnight and used it for a little bit that day. But the next day when I went to use it, it wouldn't start again. I started thinking, "the battery usually does not die that fast." So I plugged it in, started it up and noticed that up at the top, instead of charging, it now says, "Not Charging." And the battery indicator lights are off, so I'm thinking I may be in need of a new battery.

This hasn't been the end of the world since I can still use the computer when it's plugged in. But now I have to turn it on and off every time I'm not using it. Thank God it's a MacBook and starts up in about 30 seconds, compared to Jarrod's brand new HP computer he got from work that takes about 15 minutes to load everything up. Also, I have to be careful when I'm using it, because if I accidentally knock the plug out, then I have to start all over again.

I'm planning on taking it in to the Apple store this week, just to make sure that's the issue and I'm not going out and buying a new battery when that's not the problem. But, I mean, what's the normal life of a computer battery? I've had this computer about 3 1/2 years (seems ancient in computer time). It tells me I've charged the battery 400 times. Like literally, I've charged it exactly 400 times? Does it just quit after 400 charges? What's also weird is that it wasn't a slow death. Prior to this issue, it would stay charged for at least 3 hours.

I keep telling Jarrod I need to get a new laptop, but he tells me it's crazy to spend $1500 on a new one when this one works just fine, but I feel a little like a loser saying my laptop is a 2008 model. OK, I think I made myself just sound like an even bigger nerd.