Cindy,
Your right! It's a valid use of SQL. I guess it's just another example of how limited VFP's implementation of ANSI SQL is.
You could brake the query into two pieces:
SELECT TOP 3 orderid
FROM orders
ORDER BY orderdate DESC
INTO CURSOR top3
SELECT *
FROM orders INNER JOIN ordlines
ON orders.orderid = ordlines.orderid
WHERE orders.orderid IN (
SELECT orderid
FROM top3)
-Mike