There is no way to save the drivers as they are now an integral part of the system. If you have the install disks for all the hardware on your system so much the better. You will have to install them again later. If you don't have all the install disks, here's what I sugest.
Format the drive that doesn't have you OP system. Then create a folder called ... say ... "Drivers". This will leave your system intact. Next go to device manager and list all your devices. (graphics cards, sound cards etc.,).
Now, search the internet for the latest drivers for these devices and the Op system you will be installing. Save all these files to your newly formatted drive's "Drivers" directory.
When you have collected all the drivers you need, format the drive you intend installing the new OP system to. When the install is complete you can go to the drive with the "Drivers" directory and install all the latest version of drivers for your devices.