Just how valuable is a human life?

[ultimategamer]

alright, i recently got done watching an anime. one of its main themes i've thought about extensively and i couldn't come up with a solid moral (relative to me) answer.

Just how valuable is a human life? Lets say, theoretically, a group of terrorists hold a thousand people hostage, and demand that this random but innocent guy be killed or they'll kill the all hostages and you had to make the call. Yes, theres a chance they'll wuss out and won't it. Yes theres a chance the SWAT team will come in and save the day. But are you really willing to take that chance? What if the person they're demanding is a good friend of yours? your gf/bf/spouse? your father/mother? yourself? What if you raised the stakes to 10000 people? 1 million people? the world? Just how much value would you put on a someones life, based on a chance?

Logically, the best choice would be to kill that one person, and save the rest. It can't be too bad, right? However, knowing that theres only a chance of everyone actually dying, and when you bring up the stakes when it involves someone close to you is that most moral choice you can make? Is it worth taking the risk to save all those lives, or take the sure fire path and save everyone, but lose someone innocent and important to you.

Granted this type of situation will more than likely never happen to anyone, its still interesting to think as to what you would do. What does everyone think of it?