Manharawy said:
The problemis that i'm having an enviorenment consisting of more
than 7000 client PCs, doing this on each machine individualy will be
very very time consuming - if possible !!!
Yes. It will.
However, there is no software that can keep them from obtaining physical
access to the machine.
If they have a CDROM drive and and if they have unmonitored physical access
to the PC, then they can - as long as the BIOS allows (all modern ones do) -
find a way to reset the BIOS, set the machine to boot from the CD and boot
with whatever they feel like. Software has nothing to do with the INITIAL
bootup of the machine.