It's strange, isn't it? With Sony announcing that it's sold some 3.9 million PlayStation 3s over Christmas, you'd think it would be a great time right now to be a videogame retailer. But that's not the case for historic UK retailer HMV. The company as a whole has been struggling for a while, but this Christmas has hit it particularly hard, with videogame market share down some 16% from last year. And