The partition on which Microsoft Windows NT or Windows 2000 installs hardware-specific files that are needed to start the operating system. These files include the boot loader file (ntldr), the hardware detector file (ntdetect.com), and the boot.ini file.
The system partition is different from the boot partition, which contains the actual Windows NT or Windows 2000 operating system files and supporting files. During the boot process, the code in the Master Boot Record (MBR) locates the system partition by scanning the partition table.
On x86-based computers, the system partition must be on the first physical hard disk of the machine and must be an active partition (and hence a primary partition). You can format the system partition by using the file allocation table (FAT) system of MS-DOS or the NTFS file system. On a RISC system, you must format the system partition using FAT, and the system partition can be on any physical disk. In a default Windows NT or Windows 2000 installation, both the system partition and boot partition are on the C drive.