Well, the Enterprise does have shields, but a start destroyer is much bigger. In playing the old game X-Wing it seems to be pretty easy to take down a star destroyer by blasting the 2 fuel tanks on the top. I think all the Enterprise has to do is fly fast in circles around a star destroyer and shoot the fuel tanks.
Negative ghost rider that pattern is full.... Star Destroyer would win. Enterprise would have to Warp out the battle to survive.. Down with the Trekkies and all their fans...