Something I was about to mention in some reviews and I'm starting to think maybe in English it's done differently. I'd always write: "Hi" he said. Unless the descriptor isn't referred to what's been said. "Hi" he said. "Hello." The reply came from under the table.
The correct punctuation would be: "Hi," he said. "Hello." The reply came from under the table. or: "Hi!" he said. "Hello." The reply came from under the table. If you wanted to have the response one sentence, it would be: "Hello," he replied from under the table. You can check out Cogito's useful thread on dialogue for this.
Read it about three minutes ago. Also the PoV and Show and Tell threads, both about topics I mentioned in several reviews and wasn't sure if I should describe in more detail. Now I'm not afraid of the possibility of having to explain the concepts every time, I can just link to your profile.
Watch out for differences between British and US punctuation, though! Wikipedia explains them in its article on American and British English differences.