function that return multiple fields and rows

Hi All,
    I would like to write a function that returns multiple rows and multiple
fields, something like this.  I know the syntax is probably wrong, any helps
would be appreciated.

CREATE FUNCTION GetGuestbookMessages (int4) RETURNS SETOF VARCHAR AS
'
        SELECT guestname, guestemail FROM GuestbookMessages WHERE UserId = $1
' LANGUAGE 'sql';

notice that I want to return more than one field and more than one record in
the above function.  Thanks.

wooi.