Mail dissapeard after updating to 10.5.7


Has this ever occurred to any of you that after updating my MacBook Pro to 10.5.7, all of my e-mail seemed have dissapeard.

Every time I click Mail icon on the dock, it gives me this "Welcome" screen where it asks you to set up new accounts. Since I'm afraid doing so may overwrite existing .mbox file or something, I haven't done that myself.

I repaired the file permission, repaired the mail indexing, nothing worked.

Any clue???? :(