If you just want to use the garage PC as a file server then consider finding someone to help you set it up under Linux.
As a Linux SAMBA file server it'll be far more quick & secure than any Windows box.
You can stop the pretty-candy GUI, remove the monitor and keyboard and control it over the network. You can even underclock it and reduce or eliminate the fans.
Your Windows box will never know the difference.
Hey-ho....
