Is it possible to still buy a modern laptop and put Windows XP instead of whatever is preinstalled?
Well in short yes you can but i wouldn’t recommend it as Microsoft no longer supports XP which will leave your computer at extremely high risk of being hacked and obtaining vicious viruses that can steal your data or even trash your hard drive.there are plenty of how to information on the web to learn work all operating systems and youtube is the best place for free video tutorials. with Windows, its not worth getting Windows 7 as support stops in mid January 2020 and 8.1 support stops in 2023 so it is worth learning Windows 10 as this is the future and will always be supported. Alternatively you can install Linux OS which opensource which totally free and no licence needed to install and use. there is a steep learning curve with this for new users as to get the best usage you will need to learn its coding language. but youtube as mentioned before has a wealth of free tutorials which will speed up the learning curve. there is also apple OS which you can buy and install and you can learn all that you want or need on youtube.