Long before the iPad arrived, computer makers began experimenting with tablet PCs running Windows. Slates without keyboards got little traction, but convertible tablets with keyboards found a small following-largely among business users who spent a lot of time out of the office.

It has been a while since I’ve looked at these convertibles, and a lot has changed. Microsoft Windows 7 has better support for touch input, Intel’s latest chips provide better performance and battery life, and integrated 3G wireless makes these devices more compelling. The sudden interest in tablets got me wondering just how far these convertibles have come, and whether one could now be a credible replacement for both a laptop and iPad.