Think of the pain your friends and family feel. Do you really want to put them through grief? (Read this thread http://www.virtualteen.org/forums/showthread.php?t=3103
- very good explanation).
Life can get so much better. You're only 17. You have tons of years ahead of you. Why put it to waste? You have nothing to lose staying alive, but killing yourself throws everything away.
Why do you want to kill yourself? Anything is fixable. Don't give up.