I am going to geek out here for a second too. Let me first start by saying that I think trying to figure out who would win in an Enterprise V Death star is like trying to figure out who would win between a spider and my shoe. The enterprise is WAY out classed pure and simple you have one Sovereign class (or whichever Enterprise you are using) against a battle station the size of a small moon. Even trying to compare the Enterprise vs a smaller ship say the Republic's Acclamator Class. I do however think that the Enterprise would have the technological advantage in any fight vs a star wars ship.
As far as the Borg cube goes remember that Star fleet was only able to destroy the cube because Picard could hear the borg and knew the week spot of the ship. Without him the Federation would have had a much harder time taking the ship out. I think the borg's attack plan would have been something along the lines of bombard the Death Star's shield generator when it was in orbit around the moon until the shields dropped then beam aboard and start the assimilation.
Now back to reality.
On another related note I liked the movie.