"Let me check that file for you."
That's Windows Explorer building a thumbnail, your antivirus checking it out along the way and other protection software such as Spybot checking it again.
I didn't even get to how copies slow to a crawl after some thousands files in a folder.
If you want to discuss this, more details but a nod to ROADKIL's UNSTOPPABLE COPIER since it bypasses some of the nutty Windows Explorer nuttiness.
My friend has a Sony VAIO with an i7 processor running Windows 7. She is trying to backup 200 gig of pictures and video to an external 3TB WD Mybook. Her computer has been transferring these pictures for 3 days solid! I thought it should only take a couple of hours, not days.....is this correct? What could be causing this slow down?