I've upgraded my machine at some point in the last year, where I added a new
500GB drive and moved my C: partition across to it. The previous 250GB drive
was left in for additional storage.

Just recently (while upgrading my BIOS) I realised that my system was still
booting from the 250GB drive even though Windows was on the other disk.

There is a fair possibility in the not too distant future that I'll replace
the 250GB disk with a larger disk, in which case I won't be able to boot. Is
there a safe and reliable way to change it so that the system boots from the
500GB disk?

CJM