Desktop p6680t - hard drive failure

I have a friend who has the desktop HP p6680t.  I have made her the 3 recovery disks.  She has now had a hard drive failure.  I have replace the hard drive.

Will the 3 recovery disks actually work on a hard drive that has no O/S?  She had Win7, I believe, on the hard drive that crashed.  If so, do I start with disk 1 or disk 3?

Thanks for all tips and information.