Final answer:
To install Windows 7, NTFS is the required file system due to its support for larger partitions and enhanced security features.
Step-by-step explanation:
The file system required to install Windows 7 is NTFS (New Technology File System). While Windows 7 can read other file systems such as CDFS, FAT, and FAT32, it requires NTFS for its system drive due to its support for larger partition sizes, enhanced security features like encryption, and various other features that are necessary for the operating system's functionality.
For optimal performance and to utilize the full set of Windows 7 features, NTFS should be used when installing the operating system.