Replace Old Files When Copying A Folder

when you copy a folder in Windows XP, the Confirm Folder Replace dialogue appears, which only gives you the option to replace files one at a time, replace them all, or opt out (No). How do you keep the old files in the folder and add the new ones that are not there already? For example, if I am backing up My Music folder and there is 7 GB of music sitting on my external hard drive, how can I add only the 200 MB of music files that have been added since the last time I backed up this folder? I remember this used to be possible in previous versions of windows. The dialogue in XP, the way it is set up, you have to replace all the files.