Would you help your worse rival who was heading in a life-or-death situation or...?

Yes, you should help him. Show him your passionate, caring side. You would totally regret it if he really died. It might feel good that your enemy is dead FOR NOW. But you won't after a few years. How do you know? There might be an unexpected twist and you guys might be great friends after because he saw light out of the dark, desperate, scudding clouds.
As always, having one more friend is better than having an enemy.

Treasure this chance! :)

Good question and I have a quote but don't know where it comes from.

The enemy of my enemy, could also be my friend.

That's probly not exactly right but it fits.

Dallas

i would help of course,,,that person's a human too and no matter what doesnt deserve to die(at least I know of :P)

I would either leave them to their fate or help them, if I had the balls I'd make the situation a sure death, but I am a guilt driven person so I'd probably help them.

Yes, I feel that certainly I would. Despite our differences, I feel at some level that we are "all in this together" so indeed without hesitation I would help even the worst of my enemies.

As much as i despise them i wouldn't want them dead. The only thing is would they listen to you an accept your help. People are so damn stubborn.

It depends why they were my worse rival in the first place. If it was because they killed one of my family members or something like that, then no chance, it would save me from killing them myself.

yep

The quote "YOU DESERVE IT!!!" is best used in this kind of situation

depends there are a couple that i wouldnt give the sweat of my drying nuts too,

http://www.youtube.com/watch?v=0RR4mPGJ6Pg