Before I start

Hello, I have this iATKOS V7 disk which fell out of the sky on my desk, and I'm currently running Windows Vista, I've got 3 partitions, one for Vista, one for random stuff, and a 17gb for iATKOS... From what I've read if I install it now, I won't be able to boot Vista any more because my boot file will be messed up. So how will I avoid this, or how will I be able to fix it before messing it up for good. Do I have to backup something before I start installing IATKOS?

Some explanation would be appreciated

when you try booting into vista, does it say
BOOTMGR is missing?