2tb Hard drives are really cheap at the moment.. I reckon go to a computer store and get one built ground up with 2 x 2tb hard drives and a decent graphics card for the CCTV. I usually just go see Storm Computers in Cannington or Myaree depending on if I'm coming from home or work.. they are really helpful.

I have a nice quad core I built about 3 years ago and its awesome.. have done stuff all to it and it still works perfectly.. I stream all media into different rooms using either my two xbox 360's or my Ps3 across my wireless network and have just made Windows Media Player playlists for the mood.. i.e Party, Chillout, Alternative, Drum & Bass/dubstep etc etc.. its pretty easy.

It'll take you FOREVER to burn/Convert DVD's to Data files however, so I hope you have patience haha.