From the "more than you wanted to know" dept, here's a link to the Linux NTFS project's FAQ. It notes that "The original driver, in [kernel] 2.4 has some write code in it, but it is extremely dangerous to use it. The possibility of destroying your filesystem is very high."

Reading data from an NTFS partition is fine, though.

So be sure to mount it read-only (e.g. by placing -o ro at the end of the mount example given earlier). <edit> Ooops, forgot the "-o" switch; the entire command is "mount -t ntfs /dev/hda1 /mnt/hda1 -o ro"; although the mount command is smart enough that you can shorten it to "mount /dev/hda1 /mnt/hda1 -o ro". </edit>

There is a Knoppix "clone" named Linux Defender Live that includes a, shall we say, novel new utility that's actually able to safely write to NTFS partitions. It's called Captive, and it actually downloads, installs, and uses WinXP NTFS drivers from MS! (It has a GUI wizard to install them that's very easy to use.) Check it out.