Operating system help / advice / etc

Gents (and ladies)

I've had a HP 1935 for a few years and its been a superb peice of kit. I have just upgraded to a HP / Compaq 3970 (found a bargin on e-bay) as the other one was starting to feel a little slow when opening large files. Its basically brand new, although its about 3 years old it hasn;t been used. still sealed in the box.

I'm not totally sure what operating system they both use - think its windows CE 4.20???

I've heard people talk about windows 5 etc

Can the operating system be upgraded at all or is it based on the hardware?

I Wish to make the most out of the new kit so i've ordered a GPS receiver and will get myself Tom Tom or similar. will this depend on the operating system above?? I'd like to get the latest software onto it so its the bees knees

Cheers guys