Since TUG says there is no upgrade from TeX Live 2012 to 2013, it has to be a new install. However, I do not want to have two versions of TeX Live and I don't want to mess up system
PATH (Windows 7). Is it the right procedure to uninstall 2012 first, and then install 2013 ? Will other programs such as Emacs redirect link to new 2013 installation correctly?
I ended up install 2013 first, changed system environment PATH and made sure things work, and then uninstalled 2012. So I guess the order doesn't matter as long as the PATH is correct.