As I recall that episode Archer never knew who or what the Borg were. And just because Archers encounter with such aliens a hundred or so years earlier wasn't mentioned by Picard in an episode doesn't preclude his knowing something about the encounter but not making the connection.
I though it was a good episode.
The Borg weren't even ever in that quadrant. In TNG Q threw the Enterprise across the galaxy to facilitate the meeting between Humans and the Borg. That's the issue with the episode...and most prequels for that matter.
