For the uninitiated, Windows XP Sweet (often versioned 5.1, 6.2, or 8.1) is not an official Microsoft release. It is a "Windows Mod" —a customized, pre-activated, and heavily tweaked version of Windows XP created by underground forum users in the late 2000s and early 2010s.
You are looking for a ghost. A mod. A piece of digital folklore.
Disclaimer: This article is for educational purposes. Linking directly to modified Microsoft ISOs is not provided as they often contain copyrighted Microsoft code combined with unlicensed cracks.