By default, copying from the command prompt will prompt you to overwrite files that already exist in the target location.
You can add \"/Y\" to say \"Yes to all\" re
I expect xxcopy has an option for that.
Bingo:
http://www.xxcopy.com/xxcopy27.htm#tag_231
2.3 By comparison with the file in destination
The switches in this group select files based on the
comparison between the files in the source and those in
the destination. They are often used for periodic backup
and directory synchronization purposes. These switches
were originally created as variations of directory backup.
They are also convenient for selecting files for deletion.
2.3.1 by Presence/Absence
The /BB and /U switches are the two switches which select
files by the pure presence or absence as the criteria.
Other switches in the this group (Group 2.3) are also
affected by the file in the destination, but for a
particular characteristics for comparison's sake.
/BB Selects files that are present in source but not in destination.
/U Selects files that are present in both source and destination.
-Adam