I can never remember which key to hold down to copy or move a file when I drag a file from one location to another. Vista comes to the rescue with visual clues when you drag a file.
For example, when you drag a file to the desktop normally, you’ll see this (note that the mouse pointer was hidden by the screenshot utility)
Here’s the recap of the drag and drop commands:
Drag file = Move File
Ctrl + drag file = Copy File
Alt + drag file = Create Shortcut to File
Note that dragging a file only moves the file if the destination is on the same drive. If you drag a file to a second drive it will be copied instead.