want to study the Satoshi (bitcoind) code Is there any blog or document that gives a basic "tour" or "overview" of the Satoshi code?  I could just dive in but it would help to read an introduction first.
Take a look at the Bitcoin protocol specification and in more general the Bitcoin wiki. Also, the original paper of Satoshi is a good read.

EDIT: I recently found an article on Bitcoin Talk about the Satoshi client code structure. It's an interesting read too!