In newer versions of Windows like Vista and Windows 7 when you are performing a bulk operation like a copy or a delete and you get a dialog asking you about over-riding something you get an option to select the "No" option and apply it to all of the files you are operating on. But in older versions of Windows, you get a "Yes to All", "Yes", and "No" (along with Cancel usually) but there is no obvious way to say "No" to all of the files. So you can be faced with clicking "No" a whole bunch of times.

Even though it's not obvious, there is a way to say "No to All". Before you click "No", hold down the "Shift" key. If you click "No" when you are holding down the "Shift" key, it will apply this option to any further questions it has, so it's the same as if you said "No to All".