I can read the NTFS partition from Linux, but I've heard that writing to NTFS from linux can, on occasion, corrupt the partition.
I doubt it. I've been running Fedora alongside various versions of Windows for years, and always have at least one NTFS partition mounted r/w in both operating systems. So far, I have never corrupted an NTFS partition or filesystem from Linux. NTFS-3G is very stable, it's included in practically every distribution, and Fedora has conveniently linked it to mount.ntfs. Use it without fear.
I've never corrupted an ext3 filesystem from Windows, either, not even my LUKS partition, not even through multiple Windows crashes. But I rarely mount ext3 r/w from Windows, so there's not much of an opportunity for disk scribbling there.
Edit:
If you still want a new partition, use ntfsresize to shrink the filesystem, then use s/c/fdisk or parted to change the partition size. You have lots of choices, read the man pages and play with them to see which tool you like best. After shrinking the partition that holds your shrunken NTFS filesystem, create a new partition out of the missing space. Use mkfs.vfat to put a filesystem on your new partition, or reboot and let Windows do the formatting, and you're done.
Before you change your partition, you should save the partition table somewhere safe. Assuming your hard drive is sda, dd if=/dev/sda of=partiontable.sda bs=512 count=1 should do the trick. To restore the partition table, do dd if=partitiontable.sda of=/dev/sda bs=512 count=1. That
should work with good old DOS-style partition tables, I have no idea if it works with whatever fancy new disk-labeling schemes they've cooked up recently.
Really, it's easier just to trust NTFS-3G to play nice than it is to go poking around your partition table, IMHO.