Gave this some thought. Even if you find a utility to do what you want, I
would not try making the BIOS change on all 500 computers at the same time.
Try it one on PC first, if that works then try in on a group of 10
computers, then 50 computers.
I would not do any more than 50 at a time because if something should go
wrong can you imagine try to fix 500 computers and having 500 irate users
(some of which are managers that can make your life/job miserable should
they choose to do so, because 500 PCs being down can play havoc with your
company's business).
Make logical groups or areas of PCs to update and be ready for problems if
they occur.
JS