Now Voyager takes on a Borg Tactical cube, you know ...
You mean "the baby cube?"
In military parlance, tactical means small, local, lower powered, short term and flexible.
Flexible is alway good.
That was no "baby cube", here's a screen cap http://i45.tinypic.com/2ic7a55.jpg
That little blur on the left is Voyager.
That thing is at least the size of the cube that Enterprise faced. In fact I think it's bigger!
Look at the son of a brick, it has freakin armor!
This is what Seven Of Nine had to say about it.
"This is a class four tactical Vessel, heavily armed, the central plexes is protected by multi regenerative security grids..."
And she said it like "You honestly think you have any chance in hell of taking on this thing!?"
It's made clear in that episode (Unimatrix Zero) that this is not your run of the mill borg cube exploring space looking for things to assimilate. This is what the borg whip out when the kid gloves come off.
Normal Borg Cube= "Hi, we're the borg, we're just exploring. Would you like to be assimilated into our collective? We won't take no for an answer."
Class Four Tactical Cube= "We are the borg, bend over because your ass belongs to us now."