You could do this directly with the mount command.
Edit /etc/rc.local. This gets executed at startup after boot as root:
gksudo gedit /etc/rc.local
and put the mount code inside:
mount_at="/media/OS"
partition="/dev/sda3"
if [ ! -d $mount_at ] #create mound directory if it doesn't exist
then
mkdir $mount_at
fi
mount -t ntfs $partition $mount_at
where $mount_at is the folder where you want to mount to, and $partition is the name of the partition. My windows partition is at "/dev/sda3" and not "sda1" because I have a Dell with other small system partitions. To check what is the name of your windows partition do:
sudo fdisk -l
which for me gives
Device Boot Start End Blocks Id System
/dev/sda1 2048 206847 102400 de Dell Utility
/dev/sda2 * 206848 30926847 15360000 7 HPFS/NTFS/exFAT
/dev/sda3 30926848 540132512 254602832+ 7 HPFS/NTFS/exFAT
/dev/sda4 540133374 625141759 42504193 5 Extended
/dev/sda5 540133376 619132927 39499776 83 Linux
/dev/sda6 619134976 625141759 3003392 82 Linux swap / Solaris
So /dve/sda3 is the largest NTFS partition, probably the one you want.