Out of curiosity, not commitment ;), I just tried to install the SC9 WIn64 version on my everyday notebook PC. Switched the virus check off as requested, ran the installer, let it finish, opted for RUN SC9, then the dreaded Firefox message:
Unable to connect
Firefox can?t establish a connection to the server at 127.0.0.1:8090.
The site could be temporarily unavailable or too busy. Try again in a few moments.
If you are unable to load any pages, check your computer?s network connection.
If your computer or network is protected by a firewall or proxy, make sure that Firefox is permitted to access the Web.