Exchange 5.5 migration….help!

Hi All

I was asked recently to build a new server to replace the old one. OS is NT and Mail system is exchange. I have run a full backup of the previous server so now all I need to do is to install Exchange and dump the data files right? If thatsthe case then what files do i need to restore or if not whats the best way to do this? These servers are not on the network at anytime together.