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.
For instance, on your first go, drop in column 0. Then, the AI drops in columns 1, 2, 3, 4, leading to this: