The simplest and most cost effective way is to get some medium that you can back up your old system and data to: CD/DVD, USB or new HDD. Then, after you have backed everything up, you use the original windows disk to restore the old system onto the new 2 TB disk. Now, when you do this you will have an exact replica of the 640 GB disk. You will have to use a program like Partition Wizard to resize the 2 TB disk or create a new partition to allow you to access the 1.3 TB of other storage.