You have to use captive-ntfs to write to NTFS. You need a few files from Windows 2000/XP systems to make captive-ntfs work.
I think Knoppix by now comes with captive-ntfs to write to NTFS partitions because what klaus has mention at http://www.knoppix.net/forum/viewtopic.php?t=7086#32173
Like everybody said the kernel's NTFS module does not support full write support for NTFS partitions, so make sure you specify read-only when using the kernels NTFS module.
For more information about captive-ntfs go to http://www.jankratochvil.net/project/captive/