Didn't get a Welcome Screen. I got a flickering screen of NOTHING: alternating grey and black screens.
I have never heard of an upgrade killing a computer either. I'm just sitting here grading papers on my old laptop. Saw the message saying Win 8.1 now available on the new one and figured I'm here, why not? I've spent money on laptops and have also gone the cheap route. Always seem to have either hard drive or motherboard issues (Toshiba, Dell and Sony). I got this new one as my old HP Pavilion occasionally gets the blue screen of death so I figured I better buy before the semester ended and I'd be screwed.
My laptop was registered with HP. I'm currently doing the upgrades to my kid's Toshiba. At least Toshiba sent out a message saying download these software patches first before you install Win 8.1. I didn't get anything like that from HP.