Why wait for a copy of windows when you can just download the ISO from Microsoft?

Honestly, now a days USB pass through is so good that a virtual machine works well enough for firmware upgrades. Especially true if you have a separate usb controller and you pass the whole PCIe device! It's extremely rare I ever need bare metal.

-73

You can use windows in indefinite trial version with Activate Windows watermark. Grab a windows iso from the website. Put it on USB stick (I use Ventoy). And install. I would keep windows bootlaoder and grub on separate partitions.

There’s a lot of people saying not to pay for windows or not to use eBay or to download from Microsoft directly or to use massgrave instead but there are very few possibly no responses explaining why that’s a better option than buying from eBay.

First things first, and I know this is gonna get some people responding with the ol’ “nuh-uh”, but there’s compromised counterfeit install media for sale. You most likely don’t know how to tell the good from the bad. The bad can also look very, very good.

If you want to know you’re getting the good stuff straight from Microsoft, use uupdump to create an updated install media for whatever sku(version of windows) you want and use rufus to make the usb installer (you’ll need to be inside a windows vm or on your old version of windows). The reason I say use Rufus is because it gives you the opportunity to turn off some stuff like requiring a Microsoft account in the 11 install process.

Once that’s done and installed, you can activate however you like, either with massgrave or with a key for your sku purchased from Microsoft directly.

Really the only thing you have to do after installing Windows (if Linux was the first) is to reinstall your bootloader from a live Linux environment.

If it's Grub, you can look here: https://pendrivelinux.com/restore-grub-after-windows-install/

If I'm right, during the restoration of the bootloader, Grub will find your Windows installation too, and will add it to the menu.

Installing Windows will always nuke the existing bootloadet with the Windows one. You can install Linux just fine now, then Windows, but you'll need go back and set the bootloader back to grub or whatever your distro prefers. If you don't know how to do this yet, just look it up. You'll need to know how to do it in the future, since Windows Updates will randomly do this again in the future.

If windows was installed once on a motherboard if you install windows from USB again on the same motherboard even after wiping it will remember your purchase and not make you pay again

I also need some old app working only in Windows, I spent hours on wine trying to make them work, but no. So in the end, I installed Linux only, then set up a simple QEMU of WinXP SP3 image, just to install those programs (they need serial ports, and I can redirect the ttyUSB0 to QEMU as a COM1) and that's it, no more *real windows.

Why not just clone the old ssd to the new one?

No need to reinstall tbh.

Also just download the windows iso from microsoft directly. If you do not want to pay for Windows you can always just use https://massgrave.dev/

Do you have room for 2 SSDs in the case? If so, install windows on one and Linux on the other. Then set the BIOS to boot from the Linux disk and grub will let you decide which OS to boot from. This way, windows won’t interfere with Linux.

I’ve been using this for months and it works well. Except when I hit a Debian bug that configured grub to not look for OSes on other drives! But that was fixed.

Don't buy windows from eBay! You can download an iso for free from microsoft. Flash that to a USB and install it that way (or as others have suggested, just use a VM). It won't be activated but you don't need that for what you're doing: https://www.microsoft.com/software-download/windows11

If you don't need windows 11, I actually recommend 10 ltsc. It doesn't come with all the bloat and adware that normal windows comes with: https://www.microsoft.com/en-us/evalcenter/download-windows-10-enterprise

I have no experience with setting up Windows after Linux. I've always done it the other way around.

However, what version of Windows was it running before? If you haven't switched the components yet, you can use Windows to make a Windows boot flash drive or DVD officially using the "Windows Media creation Tool." It's a free download from an official Microsoft page. I don't think you needed to buy Windows 11 at all. Both windows 10 and 11 will recognize that your hardware (motherboard mostly, I believe) is registered with a license, and it will simply activate your Windows online, no hassle. It's like the one thing Microsoft got right.

Could always attempt firmware updates from within a Windows VM but I suspect your mileage may vary and there’s always the risk of bricking a device when updating firmware (and a VM may increase that risk, I don’t know).

I would echo the suggestion of others, simply add a second drive, don’t dual boot, just change the target device for boot in the UEFI settings when you need to load windows. Also, I wouldn’t bother buying windows if you will only boot it for firmware updates and that’s it — waste of money — and with what MS is doing with windows as of late (ads, Recall, etc), I have personally dumped windows altogether.

1. Stop using GRUB, it's a horrible legacy sprawling mess, most of which you don't need
2. Windows doesn't delete the bootloader with EFI boot, just make sure you have free partition space for it to create the system partition and a large enough EFI partition.