FiringSquad broke out the benchmark-o-matic and went to town on Windows 7 beta, Vista and XP. They used a pair of rigs, one mid-range and the second high end, to compare gaming performance under the aforementioned operating systems.
Right now, Windows 7 is kind of a mixed bag. While it was able to beat both Vista and XP in certain applications, it also got beat in others. 3DMark06 gave a clear advantage to XP on both of our test beds, while Vantage favored Vista by about 10%. However, real world performance brought our numbers to a much narrower margin, with Windows 7 performing admirably in both DX9 and DX10 modes. Crysis still favors Vista pretty heavily as it officially trounced Windows 7 by 16 frames per second on average on our high-end test bed. The margin was closed when we take a look at our mid-range setup, when that gap shrunk to a one frame difference.