It's real, it's seven patties tall and it's only available in Japan. Since we can't read Japanese, we defer to Laughing Squid's explanation of the greatest Windows promotion of all time:

In an unusual cross-marketing campaign, Microsoft and Burger King Japan are offering the Windows 7 Whopper during the week of October 22-28 to celebrate the release of Windows 7. Measuring 13cm (5.1 inches) in diameter, the "Amerikanbanzu" ("supergiant") Windows 7 Whopper features up to seven 113 gram (¼ pound) beef patties totaling 1.75 pounds. The first 30 customers can purchase a Windows 7 Whopper for the special price of ¥777 ($8.49), regular price ¥1450 ($15.84).

Previously on FBLA:
How To Host The World's Most Boring Party