You also might think about using a mac mini as a portal server together with your iPad 3 and apple tv.
The good thing about using a mac mini as a media server is that it works great in this setup. I've installed Plex (free) on the mac mini and connected a hard-drive to it, as well as my Qnap TS-879 Pro. On my iPad i've installed Plex as well. Now i'm able to just browse to my movies and series and using airplay to directly stream it to my Apple TV2. The Apple TV is connected to my receiver so with one click on my remote control I'm able to select which device I want the Apple TV show it's content on, on the TV itself or trough my beamer.
To sum up. The mac mini works splendid as a remote media server, it's incredible silent and doesn't consume much electricity either. You can connect multiple hard-drives to it or NAS servers and stream all the media you've stored using Apple TV with the iPad as your slick media remote control. No more hassle with cables and time consuming setups.