It has been over seven months since Firing Squad last took a look at Windows Vista performance versus Windows XP. In that series of articles, Firing Squad found that both AMD and NVIDIA's Vista performance was lacking in comparison to Windows XP, although NVIDIA's showing in Vista was much worse: Vista performance was in some cases substantially slower than Windows XP, features were missing, and SLI was unsupported entirely. Meanwhile, AMD's biggest problem was the OpenGL portion of their Vista driver, OpenGL-based games like Quake 4 scaled poorly in performance in comparison to WinXP and Firing Squad encountered numerous visual artifacts. CrossFire support was also limited.
As you can imagine, in the span of the past seven months quite a bit has changed on the Vista driver front and Firing Squad received quite a few emails asking to revisit the topic.