Regretfully your options are limited - as the previous responder said, the PDA's days are very numbered at this point.
Your other options, aside from smartphone, are pretty much going to be to carry a laptop or perhaps one of sony's UMP devices...which I dont think they even make anymore, but basically it was a slider-face laptop....very pricey for what you're talking about.
Unfortunately, my friend, your best bet really does lie with giving in to the same trend that most of the rest of the world has and getting a smartphone of some kind. In terms of doing MS Office and whatnot, you're really going to want to look into a blackberry. I know it's not the answer you're looking for - and if you can find one of the sony ultra-mini-PCs, that might be a reasonable solution for you, but I can tell you: I wouldnt want to carry one in my pocket. They're small, but they aint THAT small.