Is there a way to provoke a corrupt NTFS file system? Or how could I change the hdd's file system to any other (extX, raw) without data loss and accessible under linux but not under windows (well, at least not by default).
Each partition has a "type code" that identifies what kind of data is in the partition. (The type code for NTFS is 7, for example.) Changing the type code has no effect on the contents of the partition, but Windows will ignore a partition whose type code doesn't indicate one of the filesystems that Windows supports.
So, you could change your partition's type code to make Windows stop recognizing it. It'll still contain the same NTFS filesystem — even if you change the type code to the one for ext3, for example, you're not actually changing the data to ext3, you're just making the partition table lie about what the data is.
I'm not sure if Windows provides a way to change a partition's type code, but you can do it with the
A partition manager program could change an NTFS partition to EXT3, then this driver http://sourceforge.net/projects/ext2fsd/files/Ext2fsd/ would be needed to access that partition from windows.
You could disable and enable the driver, at will. once disabled then windows will not longer understand the EXT2-3 File System. Windows Could then ask you to Format it, push one button (to format) and it will be inaccesssable again. Is that what you want :-) The question was not easy to understand.
Partition magic was capable of making the conversion, But It would be really bad to make a conversion of that type without having a full backup of the disk your going to convert. Partition magic is not as usefull as it once was. So you should really transfer the files to some other media. once that is done many free methods can format the disk in EXT3. Then the files can be simply copied back onto the changed file system.
This answer is only a primer, a person familiar with linux would have more information.