in your /etc/fstab
you can add:
/dev/hdXX /mnt/windowsntfs ntfs umask=0,nls=iso8859-15,rw 0 0
where hdXX is the partition you want to mount...
and the iso8859-15 might have to be changed depending of the characters you use.
Be carefull depending on your kernel you might not be able to write on it as writing support is recently stable in kernels
There is as well http://www.ntfs-3g.org/ that will allow you r/w on the ntfs.