well, the new model allegedly has better processors, fans, and maybe an improved disk tray(?), so if you're going for reliability, I'd go with that. But that could all be hype and propaganda, I dunno. Haven't heard any horror stories yet, since it's still so new, but it certainly sounds appealing (particularly the quieter fan, that shit is annoying as hell).
then there's the bigger harddrive, the built in wifi, and the cool new design. Those things don't seem as important to you, but they might be in the future.
Plus, there are a bunch of really great (and cheap!) arcade games, so I have a hard time recommending the Arcade over the new one, but that's just me.