Windows XP is so insecure that you should strongly consider installing a newer operating system. You could consider installing Linux (that won’t help decrypt your files) but it will make your computer more secure.
Windows XP is nearly 17 years old. It’s pre-historic in computer terms.
You’ll either have to find a computer which you can decrypt it on or you could try running a virtual machine with a later version of Windows on it – that’s assuming Windows XP supports virtualisation.
The only other option, and I doubt it’d work, is using the AxCrypt 2 standalone version.