[Move Marquee without cutting the layer]

I realize this is an old topic, but I just stumbled upon it.  You can draw a selection from the center with the marque tool.  Hold down the option key when you make your selection.  Couple that with the shift key if you want a perfect circle or square.

 

The way to move the selection without cutting is to make sure the cursor is outside of the selection, don't click directly in the selection or the cursor adds those little scissors.  Also you can add an empty layer and make sure it's active to prevent moving anything but the selection.