Seriously guys, I don't think the disc protection software is anymore than 1-2 MB... If it was much bigger than that we'd have to wait long time for the drive to read as well as process it all (since disc protection mechanisms often use encryption).
This console idea is way ahead of it's time anyway because how big a game can be will always be subject to the size of the consoles memory, GPU & CPU speed/size. Unless of course they are just cramming loads of HD movie cut scenes onto the thing.
The average PS3 game only takes up 6GB of the 25GB disc.