We did it here at school and everything worked fine. What I did was System Rescue CD, since it had all the latest versions of QTParted and NTFS Resizer.

The only thing was when the computer rebooted, it wanted to perform a disk check, which is understood because the OS is looking for x amount of data and now there is y amount.

http://mlf.linux.rulez.org/mlf/ezaz/ntfsresize.html

Great Page!