How is the technology better? You can't just say "Hey, it's 4000 years later, it has to be better." Especially given that stuff like hyperdrive has been around for 25000 years with much in way of significant changes.
Besides, it doesn't matter if the ISD had hundreds more gun turrets (it seems like the Interdictor Class is more focused on laser turrets than turbolasers, though it does have some turbolasers), if it can severely outnumber the ISDs, both with fighters as well as capital ships.
And Death Star comes out of Hyperspace, gets its electrical subsystems fooked up by the disruption field on the planet below, and essentially becomes a giant meteor.