I am using a batch file on a USB stick to backup my pictures. I use the following command:
for /r C:\\ %%x in (*.jpg *.png *.gif) do @copy /y %%x .
Turn copy into xcopy and then you can use it's /EXCLUDE switch
copy
xcopy
/EXCLUDE
@xcopy %%x /y /EXCLUDE:\WINDOWS\
See xcopy /? for the details.
xcopy /?