I'd done my research, having investigated major Windows 8 convertible laptops on the market. The one I'd settled on, the Lenovo Yoga 13, had arrived. So last week, I went cold turkey with it on a business trip, abandoning my MacBook Air to see if Windows 8 could deliver a product that was both tablet and laptop in one. As I explained in my last column, I've long wished for a device with the "instant-on" ability of my MacBook Air but also one that could transform into a tablet, for those times when a keyboard is unnecessary. I'd been waiting for Windows 8 convertible laptops to arrive, to see if they could make my wish come true.Last week, the