Comments - Do I have totally uninstall MySQL before installing Maria?
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If you are installing MariaDB 5.5 over MySQL 5.5, the MSI should perform the upgrade. For other combinations of versions, it should install MariaDB alongside with the existing MySQL and offer to create a new service or upgrade the existing one. Please refer to upgrading-mariadb-on-windows for more detail.
Creating a backup of your data before performing the upgrade is always a good and recommended practice.
Please also note that XP has reached EOL, and for new packages compatibility is not guaranteed.