THESE days, the PC manufacturer Dell has a falling problem. Along with global PC sales, its own sales are dwindling. The former world number one is now third, behind Lenovo and HP. To make matters worse, smaller manufacturers like Asus and Acer are snapping at its heels. Even in its once untouchable portable segment, sales are falling. Dell badly needs a winner - or a slew of winners. Is it possible that the new XPS 15 laptop heralds the beginning of a turnaround?