Fedora Core 5 may either not have the NTFS kernel module enabled at all or might not have it loaded.
Look at "lsmod | grep ntfs". If there is no output try "sudo /sbin/modprobe ntfs". If that fails, your best bet is to search on this site on how to enable ntfs support. You may be able to download a different kernel with ntfs support enabled. Otherwise you may need to install the kernel source and some other packages and then compile a new kernel. If you do that, be sure you start with "make oldconfig" to carry your old .config settings to the new kernel before running "make xconfig".
There is another option. That is to modprobe "fuse" and install the "fuse-ntfs-3g" package. The ntfs-3g driver is a userland ntfs driver that has better ntfs write support. I don't know if the "ntfs" kernel module is needed as a dependency however.
Then in /etc/fstab, use the filetype "ntfs-3g" instead of "ntfs".
example manual mount:
sudo mount -t ntfs-3g /dev/sdb1 /mnt/windows/ -o uid=jschiwal,gid=jschiwal,fmask=117,dmask=007