How about?:
SELECT p.Warehouse,
CASE WHEN SUM(Quantity) >= 10
THEN CAST(SUM(Quantity) AS varchar(30))
ELSE 'There are fewer than 10 items in this warehouse.'
END AS Quantity
FROM #Product p
WHERE p.Warehouse = @Warehouse
GROUP BY p.Warehouse
SQL DBA,SQL Server MVP(07, 08, 09) A socialist is someone who will give you the shirt off *someone else's* back.