For XP, there is a way. You need to have the SP3 built 3264, then find a MUI language pack that's specifically for this version. Don't ask me where to find it, I haven't known for a long time. For Vista, I've also seen something similar.
Hello I want to switch my Vista SP1 from the English interface to the French interface where can I download the French language pack? Thank you in advance for your help.