Select Regional and Language Options , then click the Languages tab.
Since official Microsoft links are largely inactive, the is the primary source for these legacy files: Language packs for windows xp service pack 3 free download
If using an MUI, select your desired language from the dropdown menu under "Language used in menus and dialogs" and click Apply (a restart is usually required). Select Regional and Language Options , then click
Execute the .exe or mount the .iso file and follow the prompts. Note that some packs require you to be running a specific base language version of Windows XP. Select Regional and Language Options