create a new domain

hi there

a company has asked me to create a new domain to replace an old one. the company has one DC and one File server. i need your help to do the following:

(1)copy all the users and groups from the old one to new one
(2)remain all the securities sitting in the files and folder on the file server

a friend told me there is scripts do the above requirements

please i need your help soon

note: the servers is working with Windows 2003 server