I don't know if this should be posted here, but it's a good discovery I just made.
Trying to free some space from my Windows partition y deleted the C:/BOOT folder.
I donwnloaded a Vista recovery iso but hadn't a CD to burn it.
As I couldn't make grub2 nor UNetbootin boot my windows iso, I gave VirtualBox a chance:
This is what I did:
Make a virtual disk that uses the real partition as indicated here:
I run virtualbox as root, and created a VM with the proper windows version an optical disk device and the vmdk just created.
sudo VBoxManage internalcommands listpartitions -rawdisk /dev/sda
#Make virtual disk:
sudo VBoxManage internalcommands createrawvmdk -filename myos.vmdk -rawdisk /dev/sda -partitions 1,3,4
Run the virtual machine, F12 for boot options, load the iso and boot from CD.
Let the recovery disk make it's magic.
I think this could be done to install any full OS in a real partition.