If you had come here (or any other forum with some people willing to help
others) asking for instructions on how to configure a machine for
dual-booting, probably you would be told, at least, to:
1. Defragment your MS Windows partitions previously, in order to not lose any
data when resizing them to make space for the other system you want to
install; you could use the GPLv2'd UltraDefrag for that:
http://ultradefrag.sourceforge.net/en/index.html (IIRC, you can force the
moving of data from one position on the disk to another).
[Probable mid-step between 1 and 2: Reboot the system as soon as you resize
those partitions so MS Windows can test and fix them if any problem appears;
and reboot again into Windows so the fixes are consolidated. (Since NTFS is
not a well documented format, only Micro$oft, its "owner", can use it
properly. Note that it's not the user to use NTFS directly, since the system
he 'uses' is property of MS, as he agreed to it prior to making use of
it...)]
2. If you can't boot into MS Windows after installing the other system, make
sure it is up-to-date and try "$ sudo update-grub", "$ sudo grub-install
/dev/sd?".
