600dpi is BEYOND print quality -- 300dpi suffices NICELY.
I am assuming these images are for the web? If so, there's little reason to have an image greater than 72dpi as this is the resolution that MAC's display at (Windows displays at 96dpi).
If you reduce an original file from 600dpi down to 72dpi, the image will appear to "shrink" -- greatly -- and the file size will reduce tremendously as well.
Find new 'designer friends.'
