You need RAW plugs

My PC has  AMD6 Core CPU with 6G RAM， You just need plug-ins to view Nikon Raw file (NEF) with Thunbnails. There are few plugs to open DNG, NEF, and PSD with different version to compatible with Win 7 or XP.

I also have Lightroom 4.3, and CS 6 to edit files. mostly I use LR 4.

Hope it's helpful.