When you’re moving files around in Leopard, there’s no real consistent way that the files get moved. When moving files locally, they seem to move on when dragged around. When putting files onto a remote location, they seem to get copied by default. Here’s two ways to override those defaults.

Copy

While you’re dragging something, hold down the Alt/Option key. You should see a plus sign appear by your cursor. Hold that key down until you release the mouse to copy files.

Move

To move files, hold down the Command key while dragging and dropping. You shouldn’t see a plus sign near the cursor when moving files.