Would you help a stranger?

I was at Wal-Mart just now, because there's a Subway in there, and as I was eating I saw some large woman sort of lose her balance and fall over. An employee who saw this start to happen was on the ball - he rushed over and sort of caught her, probably saving her a lot of pain and suffering, though she did bump her head on a shopping cart (better than smashing it against the cart and/or ground). After a few minutes some paramedics arrived, and from the sound of things her blood sugar was low.

I was close enough to maybe help too, but I didn't happen to be looking the right direction when she started to fall. By the time I could do anything to help, there were already more than enough people crowded around, so I just kept at my lunch and minded my own business. It got me wondering though, would I have helped this woman, if others weren't already? In what case would I go out of my way to help someone like that?

I will note that, though I did nothing to help in this situation, I did feel a desire to help out. I suppose that's better (morally) than not wanting to help at all. I also wanted to congratulate or thank the employee who was on the ball.

The other day I fell - twisted my ankle as my foot slipped off the side of some pavement. It was embarrassing, and I'm very annoyed that it happened, but I didn't need assistance in any way. I don't know how I feel about this topic, nor how I really want to feel about it.