Windows XP 32-bit generally cannot see more than 3.5GB of RAM. Assigning 4GB or more to the VM is a waste of resources. 1GB to 2GB is usually plenty for legacy apps.
Launch QEMU with the empty QCOW2 image and the XP ISO mounted: Windows Xp-qcow2 Download
What to do instead (recommended, legal, and safer approach) Windows XP 32-bit generally cannot see more than 3
To help you get started with your virtual machine setup, please tell me: What is your main computer running? Windows Xp-qcow2 Download
Many virtualization fans share their own pre-configured images on tech forums. Always check the comments to make sure the file works and is safe. 3. Make Your Own
1 core is usually enough; ensure "Nested Virtualization" is enabled in your host BIOS.