I highly suggest reading the manuals, specifically the first link to the windows installation instructions:
http://pginstaller.projects.postgresql.org/faq/FAQ_windows.htmlhttp://www.postgresql.org/docs/8.1/interactive/index.html You are getting an error because either you entered in the wrong password or the database user 'christo' doesn't exist.
Do you have a "psql to 'postgres'" link in your start menu? When you click on that and enter the password you set up upon install, what happens?
Another thing: Are you supposed to be "in" psql-mode (logged in) when running commands such as createdb?
createdb is just a shell script for the CREATE DATABASE command that you can run from within psql.
-Mike