What if they built a brand new class of computer, but no one cared?  That's pretty much what's happening with Tablet PCs built around Microsoft's special version of Windows. The products keep getting better and better, but the adoption rate is stuck in neutral.   Fujitsu just released a kick-butt tablet PC – this one an ultralight 2.2 pounder.  They loved it over at PCMag.com, but even great products probably won't result in stellar sales.