QUERY Optimizer

Hi netters I have observed that the optimizer (SQL 4.0 and an On-Line 4.0 DB) is very often guessing wrong, even if we run update statistics. The estimated number of rows returned does very much depend on the sequence in which you enter the SELECT statement. In one case we had 3 different SELECT statements, which should all return the same number of rows, but the optimizer estimited the number of rows returned to 250, 170894 and 262477 !!!! Besides running update statistics frequently, are there any rules/hints which will help the optimizer to optimize instead of pure guessing. Best regards Christian Hansen