Is my battery dead?
 

Or is there something worse wrong with the electrical system?

My battery was showing a "fair" charge. It wasn't starting the car. I just went out to my car, test started the CD player and stuff after being out for the weekend. The CD player wouldn't start, none of the lighting would either. So I tried again, and it worked. So I turned on the headlights, and the second that switch clicked into place, everything died.

My car alarm light blinks while I was gone, but I was only gone for a weekend. What are your ideas?

It might be a bad ground, put some electrical grease on the battery terminals and then put the cable back on, that could be it. Sometimes my car just doesn't do anything, then you go wiggle the cables and it works! :) does the engine rotate when you try to turn it on? that should indicate wheather the battery is dead....slow rotation. But if nothing helps, go charge your battery

Well, where would the ground be? Cuz I've never had this happen before. The engine doesn't crank at all :P

it's gotta be the ground..............the black cable on the battery, just check them, put the electrical grease on. The ground is the black cable....well i dont know if it is called the ground, but thats what i call it!! haha, so make sure those cables are tight, with the grease, if you dont have grease, just make em tight, if still no power, open the hood, and wiggle the cable on the terminal...until you hear a "CLICK CLICK CLICK CLICK" or how ever many clicks, and then try it! if still no power, just try to charge the battery