Which Linux distributions do you use?

[Ether]

Originally Posted by flameout

Just to be 100% clear:

For the reasons explained by rbmj above, this command is perfectly safe.

Originally Posted by rbmj

If you've mounted the ntfs partition correctly, you're good to go. As long as it's mounted, the concept of a partition is transparent to the userland tools

What happens if the sdb1 target partition is accidentally not mounted? Will I just get an error message and no damage done? Or are all bets off, and no telling what dd might do?

dd if=/dev/sda of=/mnt/sdb1/MBR.img bs=512 count=1