You can tweak your registry to force IE to open in IE9 mode. Look for: 
HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_BROWSER_EMULATION 
  
Create a DWORD as iexplore.exe and give value 9999. (decimal value) 
Restart your IE and it will open in IE9 mode  
  
  
  
see also http://msdn.microsoft.com/en-us/library/ee330730(v=vs.85).aspx to understand these codes: 
9999 (0x270F)    Windows Internet Explorer 9. Webpages are displayed in IE9 Standards mode, regardless of the !DOCTYPE directive.
9000 (0x2328)     Internet Explorer 9. Webpages containing standards-based !DOCTYPE directives are displayed in IE9 mode. Default value for Internet Explorer 9.