Post-Sept. 11 anxiety didn't keep moviegoers from seeing the Ben Affleck nuke thriller The Sum of All Fears. Tom Clancy's latest big-screen adaptation, which finds Affleck succeeding Harrison Ford as CIA hero Jack Ryan, debuted at No. 1 with $31.2 million. After two weeks on top, Star Wars: Episode II &#150 Attack of the Clones fell to No. 2 with $20.7 million; its total stands at $232 million. Clones is performing well below Star Wars: Episode I &#150 The Phantom Menace and will undoubtedly finish the year behind Spider-Man — making it the first Star Wars pic that failed to become the year's top-grossing film. Speaking of Spidey, he came in at No. 3 with $14.5 million for a $354 million total. Eddie Griffin's well-reviewed comedy Undercover Brother opened in fourth place with $12.1 million, followed by Spirit: Stallion of the Cimarron (No. 5 with $10.7 million), Insomnia (No. 6 with $9.8 million) and Enough (No. 7 with $6.8 million).