gparted is very reliable, but you may still crash your PC because you don't put the right partitions at the right place…
Make sure you know what you are doing, and if possible, make a backup of the disk with Clonezilla before!
Creating a gparted boot USB stick
Choosing the partitions for a Windows 7 system
Do not forget the following when choosing the new partitions
It's probably better to keep the Dell/HP hidden partitions even if you don't know what they are for (you may be able to reduce their size)
If you have an accelerated disk, leave some empty space (4-8 Mb) at the end of the disk, otherwise you will not be able to re-activate the disk acceleration…
Keep 85-100 Go for the Windows 7 system C: partition
Use at least 1 extra partition besides C: and keep all the important information on this partition (not C:)
You can have a maximum of 4 primary partitions
The access to the partitions at the beginning of the disk is faster (unless you have a SSD disk)
Do you need to have some encrypted partitions?
Are you going to backup full partitions with Clonezilla?
…
Creating the partitions
Prerequisites
WARNING! If you have a mSATA SSD disk to accelerate your system, you have to disable the acceleration
A gparted boot USB stick
Steps
Make sure that booting on a USB storage is activated in the BIOS
Connect the USB stick to the machine
Switch on the machine and choose the following options
GParted live or Other modes of GParted live ⇒ To RAM
Default keyboard (Don't touch keymap)
Default language (US English)
Continue to start X and wait for the GParted graphical interface to appear
Select the disk that you want to partition in the pull-down menu
WARNING! Do not do anything if there is nothing displayed in the Used and Unused columns. It's possible that you have a cache accelerated disk. You have to disable the acceleration before you do anything else
Check the existing partitions, and decide what the new partitions should be
WARNING! WARNING! If you have an accelerated disk, leave some empty space (4-8 Mb) at the end of the disk, otherwise you will not be able to re-activate the disk acceleration…
Create the list of partitioning operations
Apply the list
Shutdown the machine, remove the USB stick and boot the machine again
Check in Windows that everything seem correct
Do not worry if Windows starts an automatic disk check during the first boot!