Darkbreeze :
You can't upgrade the firmware until and unless there is already an OS installed.
Not strictly true! That is assuming you CAN use magician to update.
I have a 840 Pro and for some reason, I cannot seem to update through magician. As a workaround, Samsung suggest i download the firmware, along with a utility, and update it in a pre-boot environment.
This means, that if you have internet access SammyJo - you could in theory, build the firmware update disk, and apply the update before installing Windows, if it makes you feel more comfortable.