The NTFS resizer is non-destructive but very dated on Knoppix (still the original, two years old version). For a while, QTParted has also safe, built-in NTFS defragmentation (data relocation) support, thus no need to defragment NTFS and unmovable data can't cause problems either.

See details at http://mlf.linux.rulez.org/mlf/ezaz/ntfsresize.html (QTParted uses this software)
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