in order to keep user computers up to date i zip the complete array of program files into a directory then send them along as zip attachment in email.
problem is i have been sending the whole lot each time. what i want to do is just send the programs that have only been changed within the last month

current command is the basic copy

Copy File c:/myfolder/*.prg To c:\myzipfolder

a) how would i modify this command to skip over programs that show no change within last 30 days
or
b) would it be better to copy all then sort by date in the zip directory then delete those older ones.

thanks for your help

k