when u use winnt.sif to disable optional componets u need the components to be present in the cd so size increases Setup first checks the sysoc then its dependancies ,that is the required infs, files specified in the infs etc. it is done in the preinitialization stage (check the optional comopnets log file) in post initilization if all are satisfied & when it is ready to install i checks for winnt.sif (which was copied to $winnt$.inf in sysetm32) componets which are marked =0, will not be installed in effect there will not be any nLitement to the CD size