There is a very small window of time on the initial boot up screen where the key to press for Bios setup is displayed. Not all machines are the same. There is sometimes a boot source option (on my machine F8) as well. I always mean to write these down but when the machine is working OK I just don't bother.

I seem to remember an option when installing Windows of creating a rescue disk. I never got one of these to work. Has anyone else?