he's got to be saying a vga is an hdmi, i totally forgot about that... who uses a 7970w  a vga or even buys a vga from a store? that mobo doesnt have a vga does it? ill have to google the model #(im not going to actually google it) if he posted it... but most likely if it has newer pci slots like a couple 16x or even one that's 2.0 it has an hdmi, i mean my laptop from 2006 has an hdmi (its a macBook pro though .  its gotta be a driver issue as he gets the tower home and puts the cards in expecting it to work but took the cards out and it worked in the store (ie he's not telling the store what the actual problem is)...a little detective work goes a long way.  don't over think anything here.  do what they did in the store then do what needs to be done to make the cards work w your system like upload drivers bc win7 doesn't have em pre installed i bet.  ::facePalm:: 

or just take everything to the store and have them do it--and they will say... Happy Mining