What are the specs. CPU speed, RAM etc?
Linux Mint 20.03 is not a LTS release(Long Term Support) and probably won’t even install on a PC made for XP. Linux Mint 20.04 which is based on Ubuntu is a LTS, as was 18.04 which is still supported and has 32 bit variants available.
An XP machine is pretty old so you might be better going with one of the lightweight versions and it’s likely a 32bit system - https://www.chippiko.com/2021/10/list-of-32-bit-linux-distro-available.html
Of those,
MX Linux is good.
Zorin is nice but isn’t as configurable as I like but that’s just me.
Bodhi and Peppermint OS are good but I think Peppermint is dropping 32bit support soon.
AntiX was weird to me but I was already used to Ubuntu variants.
The rest, I have no experience with. There are a couple of other lightweight variants of Ubuntu. Xubuntu and Lubuntu are two with Lubuntu being a little lighter.
Linux is weird due to the open source nature of it. There’s the basic Linux Kernel which is like DOS is to Windows. Command line only, no graphic user interface. Then, anyone is free to build on top of that. Debian is probably the most popular but there are others like Arch Linux, Redhat Linux etc that have a graphic user interface. Then, people build on top of those to add more features. Then finally, there are different desktop environments and those can be used with Debian, Arch etc based systems.
I run Kubuntu which runs the Plasma desktop and is a tweaked version of Ubuntu. Ubuntu is built on top of Debian. Debian is built on top of the Linux Kernel.
Linux > Debian > Ubuntu > Kubuntu > Plasma
If you already have a Windows PC and have a USB stick, download Rufus.exe - https://rufus.ie/en/
You can buy a 4gb or larger USB stick cheap. Rufus will burn a Linux OS ISO to the USB stick that will work as a Live USB. You boot the PC to that USB stick and can run MX Linux, Zorin, Bodhi, Lubuntu or whatever version as a Live operating system that is running from the USB stick. Test it out. Connect to your wifi and surf the web. Check if sound and other hardware work. Tweak the looks. See if you like it. Use Rufus to try another one and so on.
No need to buy a CD.
Go through as many as you like doing that and then decide which one you want to install. There are tons of tutorials out there on installing Linux and there are some options like keeping Windows and running as a dual boot system where you get a screen to choose between Windows or Linux/Ubuntu to boot up to. The Linux installation can shrink Windows and install itself beside it. If you decide to do that, it is best to run Windows Disk Defragmenter first as that will pack all the data together on one section of the hard drive as opposed to scattered across it.
Another option is Raspbian OS for PC which is based on 32bit Debian - https://www.raspberrypi.com/software/raspberry-pi-desktop/
Ubuntu 18.04 is supported through April 2023 and Debian Buster (10), which is what Rasbpian OS is currently based on, is supported through Aug 2022. Anything above Ubuntu 18.04 is likely to be 64 bit and probably won’t work on an XP machine.
Here’s another list of 32bit Linux distributions which has one I forgot about, LXLE. I liked it. It just looked nice out of the box. Some of the distros mentioned in this and the above article are not easy peasy installations. ie Tiny Core which comes with no graphic user interface. You have to install that later at the command line. https://www.techradar.com/news/best-lightweight-linux-distro