I would look at centralizing all your old emulation genre into an old PC, or look into other alternative platforms such as android or the classic Xbox.
That way you can upgrade your PC box to whatever without having to spend time tinkering which gets old quickly. These alternative platforms work quite well in cabinets, and can provide some distance between work or study and the dedicated session of Zelda.
Besides the faster the PC gets the harder to gimp it to play the classics. Obviously. MAME is the exception here.