For me any Linux live CD (which I put on a USB stick) will do.
I use "Clonezilla", but I don't really use their cloning tools, I just go into a shell and use dd.
First lsblk to see the names of the partitions.
Then mount your external disk if it's not already done
Then something like that
sudo dd if=/dev/sda1 of=/mnt/external
If you have Windows you should clone the Windows paritition and the 500MB "system partition" too because that is what is really bootable.
If you're using MBR then you need a standard MBR at the first 440 bytes of the disk and to set the boot flag on the system partition. If you're using GPT I'm not sure really.
But of course not everyone is as advanced as me.
Another nice Linux tool and much easier to use is gparted. It is like the partition editor in windows but much better. I think there is a gparted live disk out there that you can try.
duke-of-bytes wroteMrClass wroteUse Paragon HDD Manager
The basic version is free which allows a full backup to a file, and can restore it to another hdd even if it's a different size.
The advanced paid version allows disk to disk cloning which will save time and the need to store the backup on a 3rd disk
but wouldnt you have issues with different hardware ? i believe if the HAL is different windows wont boot correctly
It's worth a shot. I have two laptops, I swapped disks and each Windows installation was still working on the other machine. Of course they needed drivers to display the best resolution and for a few functions. Usually it works.
Same thing for Linux (even works better).
And if you install the drivers after copying your image to another computer, then your OS can now work perfectly on both computers which is kind of cool.
Both of my laptops are Intel CPUs, (i3 and i5). I can't think of an example where this would not work, but maybe with particular hardware configurations.
I believe that if you can install Windows on a machine without additional drivers being loaded during the installation, then you can also put a Window image on that same machine and it would work. I think Windows keeps the standard drivers which it has available during installation and can use these at any time.