“ Originally Posted by kaos 
”
i guess im a old ms head... lol If your like me. You have multiple copy's of ms os laying around.(I have every version of xp vista and now 7 burned and label via light scribe) what i always do whether dual booting or single partition is. I use my xp disc. clean the drive or the partition in question with it. Then reboot and pop in (in this case) your 64 bit vista.The area in question should be unallocated space now. You should be able to install now. I have always done that and never had a failure.
i have those copy too but i found it easy to do it from disk management .and i never had problems myself.But i guess everyone do it differently..