I'd noticed that the following note is included w/ the installation instructions for the Unity Extension 1.0.6.
NOTE: When using Unity on Win7 64 you get the following message in the editor: "Your 64 bit Windows installation is missing an important service pack patch. Please apply patch in http://support.microsoft.com/kb/976038 to ensure stability."
I'd recently upgraded a Win7 64 bit system to 1.0.6 and haven't noticed this message in the console or log.
There had been a frequent issue w/ this system when running Unity where Unity would crash from simply selecting across panes in the editor. The behavior resembled that described in the hotfix diagnosis. But this hasn't happened for a while now. I'm guessing that an MS update resolved the underlying issue. So it may be worthwhile to check with Unity as to whether this note is still necessary because the hotfix implementation involves some relatively sensitive registry editing and alters the way that exceptions are propagated on the system level.