that you'll be happy trying to run Sage on a PDA - even if you could, which I doubt.
PDA's are not intended to run mainstream software applications - although you'll find them with truncated versions of MS Word and Excel. The screens are far too small, navigation far too tricky, and all in all you're going to feel happier with a laptop.
I must have tried six or seven different PDAs in the last three years and I have still to find one that I would feel happy using on a day to day basis. I take my laptop everywhere I go, it's my mobile office and I couldn't do without it.