as this issue has been awhile your first reported error was...
the process could not be created for step XX of job ........... (reason 2)
As that may or may not be a permission issue I took it to be one of upgrading from 2005 to 2008.
Did you get any package errors on LOADING the 2005 package into 2008 BIDS?
If not, and you are still looking at permission issues than insure that whatever file system permissions are they are also transferred to the new system. I suspect now that you are write and reading from files not in a networked location but local to the SQL Server.