Windows 7 Professional and the World of NTFS Drives
Windows 7 Professional users can't install their operating system to drives formatted with the popular FAT file system. The installer will refuse to write files to a FAT16 or FAT32 drive, but it will offer to reformat them. New users have caused themselves a lot of grief by agreeing to let the installer format a drive, but this feature is actually a major blessing in disguise.
New Technology File System
It's not just FAT16 and FAT32 that the installer has a problem with. Windows 7 Professional will refuse to install on any drive not formatted with the New Technology File System (NTFS) protocol. NTFS isn't a new system by any means. Microsoft released the first version of the file system with Windows NT 3.1 in 1993. It took the engineers in Redmond a long time to phase out the older FAT technologies, which means that only now are users being required to use NTFS for their boot drives.
There are countless advantages to using this file system. NTFS is what computer scientists call a journaling file system. This means that a log file saves all changes to the volume before they happen, which aids the operating system in recovering after errors. This translates into a far lower risk of data loss.
File Allocation Table
Previous versions of Windows used the File Allocation Table (FAT) technology, which is still very widely used on thumb drives and SD cards. This system is extremely flexible, and it's great for NAND memory drives since it limits the number of writes caused by any individual file system operation. However, it's no longer advisable to format main operating system partitions with FAT file systems. They're too prone to data loss.
Users who are installing Windows 7 Professional on computers that have an existing operating system installed to a FAT partition will want to back up anything that they don't want to loose. The installer will completely erase this partition's file system when installing a new copy of Microsoft Windows.
Extended FAT Partitions
Other partitions on a hard drive can be formatted to the FAT16 or FAT32 file systems without any trouble. Windows will still be able to read these. That makes the file system attractive for additional data partitions. Some users might run across the exFAT file system, which Microsoft designed for removable drives. Windows will have no problem working with drives formatted with an exFAT utility, but it won't install to exFAT partitions.
Partitioning a Drive
It's perfectly acceptable to have multiple partitions on a single hard disk. Some people install the English and French versions of Windows to separate partitions on a drive. Users might also want to consider having a separate data partition to store files from. Spend some time carefully considering the way a specific Windows drive will be partitioned. It's hard to go back and change it later on.