Newbie question about plugins Chicklet and Sociable

Chicklet and Sociable are plugins that seem to do much the same type of thing–to make it easy to subscribe to a blog.

Chicklet appears presents the buttons in the sidebar while Sociable displays them beneath the article.

Here’s what I am not clear on.

1) Do both plugins do pretty much the same thing or is there an nuance that has not sunk in yet?

2) Is it advisable to use both plugins at the same time or would it be considered overkill?

3) What plugins do others use to accomplish the same thing?