They have them also but appears not as many folks notice them, had two machines. Best bet is to have them plug it in before you buy so you can check it out. Pay attention to the bottom and right hand corner. Easy way is to just turn on a machnine and set the background to solid white.
The problem with that is that you have to set up the OS first. I'm not sure what other Apple Stores are like, but there are three in my city, all of which are packed like a sardine can from the moment they open the doors to the moment they kick everyone out, so this is quite inconvenient for both parties.