Q: How can I write data on NTFS partitions?
A: Knoppix 5 supports write access for NTFS partitions using libntfs and fuse. While preliminary results show generally good stability and a low likelihood of data corruption on the NTFS partition, these libraries are still beta and there is risk of data loss and disk corruption (back up your data first). Knoppix (and the Linux kernel) can read NTFS partitions just fine, the danger is only present when attempting to write to it.
Older versions of Knoppix can be forced to write to NTFS partitions, but at great risk of scrambling the underlying NTFS filesystem (Captive NTFS used the existing NTFS drivers from a Windows system to acesss the NTFS drive, but was slow and unstable.)