And the problem with GRUB is that will soon crash and I don't know if I would boot again Vista.
I don't know what you mean by this. If you have GRUB in the first disk, the installer should have set everything up to dual boot Windows and Linux.
I would just boot up the computer and see what happens.
The normal way of removing GRUB is to simply install a different boot loader. For example, you can re-install the Windows loader by booting from the Windows CD.
But first, try it the way it is.....