I got a laptop with Linux on it with grub (whatever that is)
Now I have a Windows 7 Ultimate (Sp1, what that is…) CD, can I install Windows 7 Ultimate on it, since Linux and this grub is on it?
Grub is just the boot loader.
You can install Windows on it normally, this is not a problem, but Windows will definitely delete the grub, with which you either have to reinstall it or you have to enter the Windows boot loader for Linux if you want to have both operating systems.
If you only want Windows, just reformat the whole disk and install Windows normally.
Would not recommend Win 7.
Okay, would you know how to format the hard drive because I don't have a password etc. So that I can get into Linux myself.
I completely missed the 7. Yes Windows 7 is no longer recommended.
Insert the Windows USB stick, boot from it and then it will ask you where you want to install Windows. Simply delete all partitions on the disk, then there's unallocated space, select and Windows then creates the optimal partition scheme.
Btw as goldman mentioned, Windows 7 is no longer recommended for productive use, so you shouldn't go online with it anymore.
Installation is definitely possible, but there are two things to consider.
1. Partitions
The Linux system probably uses the entire disk. If you do not want to delete Linux, you need a second disk for Windows or you reduce the partition for Linux so that there's still space for Windows. The latter is only possible with a separate Linux system, usually If you take a live system on a USB stick.
2. Bootloader
If your Linux uses UEFI (this is the case if the / sys / firmware / efi folder exists), you can have several boot loaders and thus simply install Windows alongside Linux. Otherwise Windows Grub will be deleted and the Linux system can no longer be started. It is best to replace the Windows boot loader with Grub, because the latter can easily start both systems.
Here's what I would do:
Download the Linux Mint Cinnamon ISO (the most popular) for free and bring it to the USB pen with Etcher (if your second computer only has Windows), boot the Linux computer live and save the / home folder to USB with the file manager. All your data is in there, a password is not needed.
Install some Windows and deactivate the driver for WLAN and Ethernet so that the Windows malware does not cause any problems.
Then boot from the Mint USB pen, select Install on the Mint desktop, select "Install Linux next to the old system", then Mint will also be installed automatically next to Windows and you can select the OS each time you start your computer. For web, mail and office activities, I would only use the well-equipped and secure Linux - according to the BSI, it doesn't even require a virus scanner.
Linux can also be fully used by the USB pen, i.e. Without installation - only the free Linux can do that.
