Upgradation of Navision 5.0 Dynamics Nav 2009

Hi all, I need to do Upgradation of Navision 4.0 customized Db and ,Navision 5.0 Customized Db in to dynamics Navision 2009 version .Which upgradation method is easier ??. I read about the PDF new custom version(Merge the customizations into the new Microsoft Dynamics NAV database, which inthe Developer’s Toolkit is called the New Custom version) . Is this upgradation is easier. please help me out for the what are the steps and Procedures for following for Upgradation Process Many thanks to anyone who can give me solution for this task !!! Subha