pgsql function doesn't work

Hi,

the function bellow is created successfully, but executing it forces the
following error message:

WARNING: Error occurred while executing PL/pgSQL function
drop_table_if_exists
WARNING: line 5 at select into variables
ERROR: parser: parse error at or near "$1" at character 34

CREATE OR REPLACE FUNCTION drop_table_if_exists(TEXT) RETURNS BOOLEAN AS '
DECLARE
rec RECORD;
BEGIN

SELECT INTO rec off_mitarbeiter_id FROM $1;

IF FOUND THEN
EXECUTE ''DROP TABLE'' || '' '' || $1;
RETURN true;
END IF;

RETURN false;

END;'
LANGUAGE 'plpgsql';
select drop_table_if_exists('off_jahres_abr_2003');

If I hardcode the table name istead of using $1, everything works fine.

Please help.

Thanx Erwin