Downgrade from windows 10 to xp for free?

You can't. There are no drivers for XP. It hasn't been supported by anyone for years (including Microsoft). The hardware on your device WILL NOT run under XP, due to no drivers.

Time to find some new games.

XP isn't free...UNLESS you have Windows 7 Professional or Ultimate. then you can run XP Mode, which lets you have XP on 7 in a Virtual Machine.

You cant.
You cant buy a license for Win XP. Even if you could it wouldn't work!
Win 10 uses secure UEFI boot process. Win XP uses BIOS. The system will never boot.
Even if it does boot, you can not get drivers that work in XP for the hardware that is in use in your new Win 10 laptop. So you wont be able to use the hard drive, mouse, USB port, wifi, network port, monitor / screen etc.

XP is not free. It may be old, but it's still not free. So if it has to be free, you're done before you even start.

Try running your old games in compatibility mode (Program Compatibility Troubleshooter). This is successfull on about 75% or more of old games.

If that doesn't work, then you should look into DOSBox or Virtual machines

I have a legacy graphics program that requires XP and my laptop wasn't doing it. I went to Ebay and bought a computer from a store called siliconxchange. It's Core2, 4 gigs, XP Pro, stripped clean with a fresh install of everything. I paid $109 + tax and picked it up. He has systems for under $100. It's a real nice, clean system for cheap. I have no connection, I'm just a satisfied customer. That is just the CPU, nothing else.

windows sucks.

I have a legacy graphics program that requires XP and my laptop wasn't doing it. I went to Ebay and bought a computer from a store called siliconxchange. It's Core2, 4 gigs, XP Pro, stripped clean with a fresh install of everything. I paid $109 + tax and picked it up. He has systems for under $100. It's a real nice, clean system for cheap. I have no connection, I'm just a satisfied customer. That is just the CPU, nothing else.

get a dvd of xp and find an old computer which has a xp key sticker and use the key.

weffefewefw