By Stephen M. Silverman
Updated October 02, 1998 12:00 AM

It’s taken the U.S. Marines to unseat Julia Roberts from her three weeks on top of the weekend box office charts. The military drama “Rules of Engagement,” with Samuel L. Jackson and Tommy Lee Jones, is Monday morning’s No. 1 movie. Julia’s “Erin Brockovich,” the former champ, is No. 2. The final score, according to studio estimates: