Broadly, the following limitations apply :-

Under Windows NT there are restrictions on the size of the boot partition (the first partition on the drive). During installation, Windows NT always first creates a FAT partition. Even if you tell NT that you want to install to an NTFS partition, it first creates a FAT partition and then converts it to NTFS. Since the maximum size of a Windows NT FAT partition is 4 GBytes, this limits the size of your boot partition as well. Even if you use a third-party tool to increase the size of the partition, Windows NT can't boot from a partition larger than 7.88 GBytes, regardless of how you create it (this is associated with Windows NT's older design.

Converting to NTFS
If you've read this article and wish you could use NTFS on some of your partitions that already contain data, you can easily convert a partition to NTFS. To do so, open a command Prompt window and type the following command:

CONVERT drive: /FS:NTFS

For example, if you want to convert your D drive to NTFS, you'd type:

CONVERT D: /FS:NTFS

Note that there are some differences between the NTFS used by Win2K/XP (version 5) and WinNT. You need to apply Service Pack 4 to Windows NT in order to access NTFS version 5 drives and its capabilities.