i installed CorePlus-4.2 on a 8GB usb CF.
everything works cool. i can move files back and forth between the CF and PC hard drivet which hosts another much more loaded CorePlus-4.2.
the installation on CF is meant to light-weight, so after i installed necessary softwares (X window, wifi, xfe), i checked the disk usage by using xfe->directory properties of /mnt/sdb1/, it says 192MB, this is a bit surprising, then i checked each sub-directory under /mnt/sdb1/, they add up to a little bit under 50MB which is what i would expect.
so, my question is, as you already guessed, where does the difference come from?