Currently, there are 2 versions of each Windows 7 edition, be it Windows 7 Ultimate or Windows 7 Home Premium, Microsoft offers the consumer 2 choices: 32-bit Windows or 64-bit Windows. In essence, 64-bit Windows handles more RAM (Random Access Memory) in a more productive way than 32-bit Windows. 32-bit Windows 7 possesses the ability to utilize up to 4 GB of RAM (Windows 7 starter only handles 2 GB on both editions); inserting more RAM is senseless and unavailing. On the other hand, 64-bit Windows 7 Home basic harnesses up to 8 gigabytes, Windows 7 Home Premium takes advantage of up to 16 gigabytes, and Windows 7 Professional, Enterprise, and Ultimate can each handle up 192 gigabytes (no consumer grade motherboard can handle half of that).
However, certain software and drivers are not fully compatible with 64-bit Windows, while a vast majority of software and driver (99%) are compatible with 32-bit Windows. Fortunately for high RAM users, most software and hardware manufacturers are devising 64-bit compatible products due to the overall increase of RAM in consumer products requiring 64-bit operating systems. As a rule of thumb, not all old software will be compatible with 64-bit Windows 7, but 99% of new software will. Overall, the better choice remains 64-bit Windows 7 due to its greater RAM capacity becoming a great advantage in a world where software steadily requires more and more RAM.