ENT: Regeneration, streamed on Netflix.
After my initial "The Borg? Again? Really?" reaction, this turned out to be a pretty good episode. It nudges me a little toward the position that Enterprise takes place in an alternate timeline that was created after the Borg attack on Bozeman in First Contact. This may explain why the Borg are unknown to Picard and Starfleet the first time around in Q Who, since the events of FC had not yet taken place.