First, I followed the upgrade directions closely but the unit went dead. ViewSonic very kindly fixed the problem or perhaps they gave me a new one for free.
Most but not all software worked, but that's OK as I only had a couple of freeware installed. I upgraded the *.net utility and this helped, and was able to run some old programs, but eventually I reset the unit to factory settings and got rid of old applications. This was because of constant freezes.
I can live without those 2002 applications, but I had just bought a Targus IR keyboard and although it worked fine in 2002 it ceased to work when the OS was upgrade was installed. I have been trying to find a solution ever since I switched over to PPC 2003, and have upgraded the present Targus KB drivers, but none work. It seems as if the IR connection does not work. The KB shows in the programs window, but it does not activate the KB.I am not sure how can I check that in the ViewSonic, but Targus tells me that the PPC2003 is incompatible with their KB. ViewSonic has not responded. The batteries are fine.