We do always try and transport plasma vertically due to weight of the glass. We did have one that was shippe don its side in the van and upon opening there was a large crack in the panel...Whether it was like that before it arrived with us who knows?
I bought mine from watford and moved it to leicester without the box by having it well wrapped in bubble wrap and having it face down in the boot. It's a 42" so not exactly a small screen.
