[CentOS] Reinstall Windows but preserve CentOS

    I have a computer that dual boots between Windows and CentOS. Each 
has it's own hard drive.

    I suddenly have a problem with Windows, and may need to reinstall. I 
need it for applications like After Effects, Premiere, and other things 
that I am currently in the middle of a project with.

   It seems the system has become usnstable, it's preventing me from 
continuing to work, and I may need to wipe the Windows partition clean 
and start again.

    My concern is that if I do that, I will lose the Grub boot loader 
and not be able to access CentOS again.

    How can I reinstall Windows with a clean partition, and preserve my 
dual booting?

Dave