When NT4 came out, the best defragger for it (Disk Keeper) was built by Executive Software. They designed and built the one that comes with XP and it handles NTFS.
The 2002 Manual is on the CD and is viewed with Acrobet. This is extracted from it:
"In Windows NT, Windows 2000, and Windows XP, the fragmentation level is determined by the formula: [total file fragments]/[number of files],expressed as a percentage. Unfragmented files are counted as single fragments. You may also see different statistical reporting with Executive Software's Diskeeper, or the built-in defragmenter that is included with Microsoft Windows."
My interpretation of that is a "yes" to your question. It does support XP. Now . . . whether or not it works correctly is another matter.
