Setting up PostgreSQL on a new Mac

[shoemosher]

Just got a new Macbook Pro, trying to set up on it with my existing account. I'm entering the following info:
Server:localhost
Database User:postgres
Port:5432
Password:dbpass

When I enter that I get a message that reads "Unable to connect. Unable to connect to this database. Please check the configuration."

Anything anyone can recommend to do here?

[kraada]

Is PostgreSQL 8.4 installed on the machine? (If so you'll see a PostgreSQL directory in the Applications folder.)