looking up field names

I am building a custom field engine.  But I want to stop the user from
creating custom fields of the same name as a standard field in the table.

Would this suffice to find if a column already existed in a table:

SELECT  count(*)
FROM    pg_attribute, pg_class
WHERE   pg_class.relname = '<table to check>'
    AND pg_class.reltype = pg_attribute.attrelid
    AND pg_attribute.attname = '<column name to check>'

Thanks in advance

Terry Fielder
Network Engineer
Great Gulf Homes / Ashton Woods Homes
terry@greatgulfhomes.com