Grab a kernel with built-in NTFS support, or load the NTFS module for non-compiled in kernels. then in your /etc/fstab, mount the drive with the rw tag. i.e.:
/dev/hda1 /mnt/windows ntfs rw,uid=1000,gid=100 0 0
which automounts the drive with read / write access and changes the owner from root to user with id 1000 (good for actually writing as a non-root user).
Please note. NTFS writing is buggy and CAN AND MOST LIKELY WILL corrupt that filesystem.... use fat16 instead, or map a NTFS drive through a samba share.
If you must write directly to the NTFS partition, run ntfsfix (part of the ntfstools package) after every write to the NTFS drive, otherwise you can be in for some craptacular crappiness.