In Mac OS X, there are two ways to move or copy icons from one place to another: by dragging them, or by using the Copy and Paste commands.
You can drag icons from one folder to another, from one drive to another, from a drive to a folder on another drive, and so on. (When you've selected several icons, drag any one of them; the others tag along.) While the Mac is copying, you can tell that the process is still under way even if the progress bar is hidden behind a window, because the icon of the copied material shows up dimmed in its new home, darkening only when the copying process is over. (You can also tell because Tiger's progress box is a lot clearer and prettier than it used to be.) You can cancel the process by pressing either ⌘-period or the Esc key.
If you're copying files into a disk or folder that already contains items with the same names, Mac OS X asks you individually about each one. ("An older item named 'Fiddlesticks' with extension '.doc' already exists in this location.") Note that, thank heaven, Mac OS X tells you whether the version you're replacing is older or newer than the one you're moving.
Turn on "Apply to all" if all of the incoming icons should (or should not) replace the old ones of the same names. Then click Replace or Don't Replace, as you see fit, or Stop to halt the whole copying business.
Understanding when the Mac copies a dragged icon and when it just moves the icon bewilders many a beginner. However, ...