Why the aversion to letting Windows reduce the size of the NTFS partition?

My rule of thumb is to use the Windows tool to create/edit NTFS partitions and use a Linux tool (GParted) to create/edit Linux partitions.

So in this case I would use the inbuilt Windows 7 tool to reduce the NTFS partition and create some free space. Then I would use GParted to create partitions for Linux in the free space.

Why do I suggest this? Well, Microsoft do not release all their knowledge of NTFS and I am not convinced GParted developers have been able to glean it all with the confidence I require.