I want to note that you can win every time by dropping wherever first, then on your next moves dropping every piece on top of the AI's pieces.
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.