A restore is the simplest - but there may well be a script you need to run after the restore (see below).
As to the datatransfer packages - what do you mean? If this is packages that run on the source system that you want to be able to run on the 2008 system - then the packages need to be written to be portable i.e. no connections or environment specific data hard coded in the packages - then just change that data when they need to be run on the 2008 system. You may also have a dts/ssis issue.
This is also a lot easier if packages are held as files rather than in the database a it's just a matter of a file copy.
DTS - only when needed and never to control.