I don't see why the data is split between the two tables. It would be easier if they were both in the same table. You would have only one full-text catalog and you can specify the two columns in the same CONTAINS query.
That said, continue to use the CONTAINS function. Just use a double WHERE clause. For example,
[font="Courier New"]SELECT
desired columns
FROM
desired table(s)
WHERE CONTAINS( query here )
AND CONTAINS( query here )[/font]