Dualbooting

How do I set up a dualboot with Windows after installing openSUSE first?

With difficulty because Windows always expects to get precedence, e.g. to be on the first primary drive. Unless anyone knows any better, I would suggest you save your data from your openSUSE installation, install Windows and then reinstall openSUSE.

Hi
What version of windows, is this a newer machine with UEFI or are you using legacy boot.

Can you install a secondary drive if legacy and run windows on that?

It depends.

On a UEFI box, you might only need to change the boot order, possibly in BIOS settings.

On a legacy MBR box, if opensuse boots from a partition you might only need to change the active bit. Otherwise you might have to do a recovery reinstall of grub2.

Unless you are playing high end Windows games why not install Windows in a VM Virtualbox is easy to work with

Thanks everybody, but I just installed Windows and then Linux. I was just worrying because reformating your SSD is not a good idea, but it worked out fine.