To set or not to set?

Not "just" a question for bass fisherman but, "all" fisherman, whether it's
bass or crappie or stripers. Since I'm new to the fishing scene, I'm trying to
suck up all the information that I can, using this newsgroup (which kicks a**),
books video's, TV etc. One thing that I'm still kinda confused about is setting
a hook. Some people say "let the fish take the bait and run with it a bit and
the hook will set itself." While others sware by setting a hook as soon as they
feel a "nibble." Does the technique change when you fish a different type of
fish or should it be the same for just about anything?

So...in short, should I set the hook or not???

Thanks.

Brian in Maryland