There are 2 main reasons for installing Windows first:
1 - The boot loader
Configuring the Windows boot loader to load Linux is a royal pain in the butt. It completely overwrites any boot loader that is already there, so if you have Linux installed already you can no longer boot Linux without playing around for hours or reinstalling Grub from a boot CD.
Most Linux distributions, however, will automatically configure Grub to include your Windows installation giving you easy access to Windows without any messing around.
2 - Distro tricks
Some Linux distributions will automatically detect that you have Windows installed and give you the option to import user accounts, settings and files into your new Linux installation.
Borrowed from majenko
So i would say it is easier to do a Windows installation first folowed by a linux Install
If you still Want to Proceed with "The not so much travelled Path"
Here's the general outline:
- Make space for Windows
- Install Windows
- Reinstate GRUB
- Mount the
- Install the boot loader
Open up GParted, and make sure that you have at least 20 GB available for Windows , either as a partition you can remove, or as unpartitioned space. If it's a partition, remove it from GRUB to make sure it doesn't break your Debian install -- GParted will complain if anything bad is about to happen. Make note of current
/boot device. If that doesn't show up there, make note of the
/ device. The device name is something like
Install Windows into the space you just made
Load up from your debian live CD, and then run these commands.
If you DO NOT have a separate
sudo mount /dev/DEVICENAME_FROM_STEP_ONE /mnt
sudo rm -rf /boot # Careful here, make sure YOU ARE USING THE LIVE CD. I tried it, it works.
sudo ln -s /mnt/boot /boot
If you have a SEPARATE
sudo mount /dev/DEVICENAME_FROM_STEP_ONE /boot
Then continue with those commands:
sudo apt-get update && sudo apt-get install grub-pc
sudo grub-setup /dev/sda # NOTE THAT THERE IS NO DIGIT
sudo umount /boot
And restart. It should work fine and boot both systems.