Dual Booting Linux and Windows

Hi,

I have windows8 and xubuntu installed in my system.
(Not virtual, but dual boot.)

1.> I need to re-install windows8 as some of the system files have become corrupted. I want to do the same without having to remove xubuntu partition.

Is there any way i can achieve it.

2.> I can re-install windows, but it will over-ride the bootmgr. Can i recover it?

Any suggestions are really appreciated.

Thanks.