Hd radeon 3870 crossfire vs hd radeon 5870

Hello my minions...im upgrading my laptop from an hd radeon 3870 crossfire too a hd radeon 5870. Will the upgrade be worth it.? Will I see a significant performance boost? I need my tech minions on this one. Also...I demand refreshmants. Best minion answer will be promoted to cannon minion...recieve a salary raise and get free poro snacks every tuesday for the rest of his little minion life....minion with the worst response will be fed to the baron....heuw heuww. >:)