Should we kill healthy people for their organs?

Suppose Bill is a healthy man without family or loved ones. Would it be ok painlessly to kill him if his organs would save five people, one of whom needs a heart, another a kidney, and so on? If not, why not?

No, that would not be okay. Firstly, like everyone else has said, no one is in the position to condemn an innocent man to death. Secondly, we do enough of taking from the healthy and protecting the weak.

Consider another case: you and six others are kidnapped, and the kidnapper somehow persuades you that if you shoot dead one of the other hostages, he will set the remaining five free, whereas if you do not, he will shoot all six. (Either way, he'll release you.)
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This is actually a tough one. When it comes down to it, either 1 person will die or 6 people will die. I'll choose the one where I shoot one to save the rest.