My first PDA was running windows CE 2.1. I was running NT4.0 and MSoffice 2000 on my laptop at the time and my pda had a 200MHz cpu and my laptop 233MHz. I started looking at NT embeded and wondered why I couldn't just have Nt4 and Office 97 on my pda, it had enough power to do it.
I started messing with wearable systems and such and could find whole computer systems that would fit on a gum stick sized form factor, but MSwindows was always the limiting factor, either took too much cpu/ram/disk or the bug in early xpembedded that wouldn't let it run from read only.
Thats one of the issues that brought me over to Linux and open source, there was no forced upgrade like windows and the linux kernel will run on nearly anything. Android is the closest I've come to having the on my desktop and my pda. I can access the console and root my phone so the next step is to take a simple linux tool and recompile it for the phone and see if it will run outside the jvm running android.
Once you get off of the Microsoft/Apple closed model it becomes possible to make things happen. All thats needed is to make a window manager that will work with the phone's hardware and use it instead of kde/gnome.