copy mail folder to new mac "file already exist"?

i am setting up a new leopard install and i copied the plist for mail and the mail folder but although their is no mail folder yet on my new machine whenever i go to copy the mail folder to the new machine i get "9876.emlx" etc.. already exist and doesnt give me the option to overwrite?

i have the mail and plist from the my old machine on an external.

i have searched for the file that supposedly already exists but i cant find any of them?

thanks for any help

try,...

sudo cp -R /Volumes/external_hd_name/path_to_mail_folder/ /Macintosh\ HD/Users/your_username/Library/

...all one line command

It will ask for password of logged in user, if password = none then just hit enter.

thanks i decided to just use my xp side to copy the stuff to my mac folder so it didnt give me any problems