Hi Inspector, if you buy the SSD aftermarket, I recommend setting up the Windows OS on the SSD. As FJ suggested, you can use the HHD for additional storage instead.
This would involve either reinstalling windows on the SSD or using the Samsung software to copy the Windows OS from the HHD to the SSD.
I've not used the Samsung software so I have a question for FJ, does the SSD need to be a larger or equal size as the HHD for the Samsung software to work?
You may need a second SATA cable to accommodate the 2 drives.
The disk sizes do not have to match.
As long as the total used space can fit, the software will adjust the image size to match the target (SSD).
I upgraded my WinXP PC to SSD. The original disk was 500GB, and the SSD is 128GB. I installed the SSD on the SATA bus (requires both a SATA connection and power connection, just like any SATA disk drive). I loaded up the software under windows, and told it what to copy. It rebooted and cloned the boot drive to the SSD. I rebooted from the SSD to verify it was good, and then removed the old boot disk.
Most PCs today allow you to specify the default boot device/boot order. That lets you put the SSD on any vacant SATA port to clone and boot from it. Make sure you put it on the fastest SATA port. If you have SATA 2.0 and 3.0, make sure to use the 3.0 port to get 6 GB/Sec speeds.
If you are getting a new PC, it's probably better to do a fresh Win10 install, but there are pros and cons. That means downloading all the latest drivers, losing any cool "bloatware" programs from the manufacturer, and losing the "restore" capability most PCs have using the factory image on a hidden partition.
If you don't need the extra disk storage, you could always keep the original boot disk in storage as backup. Then if you get a virus or need to restore the original image for any reason, just go through the clone process again.