i was recently fixing some problems with an application i develop, and at the moment im stuck with the version of NTFS of the partition on which the application resides. if you do a fsutil fsinfo ntfsinfo c: you will see which version of NTFS you have. i tested it on XP SP2, the version is 3.1 on ntfs.org they say that beginning with win2k, the OS supports NTFS 5. this version has a feature (sparse files) that probably interferes with my application. the problem is that i havent seen a system with NTFS 5, or NTFS 5.1 [which is the latest, as far as i understood], so i cant test my program in that situation. how can i convert from NTFS 3.1 to NTFS 5.1 ? and which OS really comes with NTFS 5?