Slightly OT, but is it really that difficult to tell the difference between Windows Server 2008R2 and Windows 7? The linked page doesn't seem to be able to tell the difference between the two.
The product token for Windows Server 2008R2 and Windows 7 is the same (6.1) so there’s technically no way to tell the difference. jsPerf is supposed to show you it could be both, not one of them. Is this bugged?
Could you not do something with the user agent or do you get that already?
Here is a MSDN post that examines some of the platform tokens http://msdn.microsoft.com/en-us/library/ms537503(VS.85).aspx
OT, but, is there any way to embed the results dynamically?