[HLUG] mounting an external HD

[graham]

Hi all
I put a backup of my Linux system on the same HD as a backup of a widows 
system. Now trying to see the contents with my Linux OS seems to be 
impossible. I get this message:

LogFile indicates unclean shutdown (0, 0) Failed to mount '/dev/sdb1': 
Operation not supported Mount is denied because NTFS is marked to be in use.
If you don't have Windows then you can use the 'force' option for your 
own responsibility eg type on the command line
mount -t ntfs-3g/dev/sdb1/media/New Volume -0 force
or add the option to the relevant line in the /etc/fstab file:
/dev/sdb1/media/New Volume ntfs-3g force 0 0

Questions:
What risk is attached to using the force option for mounting the HD?
If I do mount it will I then be able to look at both backups?

thanks
Graham