For instance, on your first go, drop in column 0. Then, the AI drops in columns 1, 2, 3, 4, leading to this:
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . X X X . . . X O O O O . .
After trying it now, the AI actually tries harder to beat you, and my previous method is not effective anymore.