The simplest method is to get your old hard drive out of the old machine, then once your new one arrives/ is built, put the old one in as a secondary drive, remember to ensure in bios that you can only boot from the new systems drive,
then boot into windows and copy across to the new drive,
if you get problems with permissions, put the new drive in the old machine as secondary, boot into the original windows then transfer that way
or if you have both machines there, simply use an external/spare hard drive to copy from and to
Moto