Windows XP supports three different file systems – FAT, FAT32, and NTFS. Although the FAT32 file system is a reasonable and well-performing file system for large partitions, it does lack one key feature, namely security. In order to be able to secure files and folders with security permissions (as well as use features like file system encryption and compression), you need to be using NTFS. Many vendors ship XP systems with all partitions formatted using the FAT32 file system, but this doesn’t have to be an issue. Windows XP includes the command line CONVERT utility to allow you to convert existing FAT or FAT32 partitions to NTFS without losing any of the data stored on those drives. In other words, this command avoids the need to format any partitions to change the file system.
To change a partition like D: from FAT to NTFS, type CONVERT d: /fs:ntfs at the prompt and let XP change it. If the drive is currently in use, it will be convert when you next reboot. Note that the CONVERT command can be used to convert FAT or FAT32 partitions to NTFS, but not vice versa.