RIS Images Not Available

I created 2 Ris images (Win XP). One is a standard CD and the other one I
deployed the standard CD on a reference pc, then I installed all the patches
and applications. Then I launched riprep.exe to send the image back to the
server, but when I boot up with a pc other than my reference pc I'm unable to
see the image created with riprep. Only the standard CD RIS image is
visible.
Computers are not the same but they have the same HAL.

HELP!!!

Thanks, Frank