: The 64-bit architecture, allowing the OS to utilize more than 4GB of RAM.
This stands for . Windows 7 came in multiple editions: Starter, Home Basic, Home Premium, Professional, Enterprise, and Ultimate. The Ultimate edition is the "Swiss Army knife" of the consumer line. It includes everything from the Professional edition (like Windows XP Mode and Domain Join) plus the features of the Enterprise edition (such as BitLocker Drive Encryption, AppLocker, DirectAccess, and multi-language user interface packs). If you wanted the absolute maximum features without purchasing a volume license for Enterprise, you bought Ultimate.