Posted By John Ridd
I'm currently working with a company looking at the use of hand held equipment in the field, and which (in size) comes somewhere between a palm held and a laptop. Their problems are possibly very different to your considerations, but without more info on the expected function and use of your PDAs it is difficult to give advice.

There will, no doubt, be the ususal speed of access and image visibilty issues (particularly under different lighting conditions) - be sure the software is specific to your purpose and that the user doesn't unnecessarily have to 'make-do'.

Is there a need to enter text? If so, one of the plug in keyboards will be essential.

Will it be sufficiently robust for the intended application?

Is there a need for extended use? In which case there may be static postural issues for the supporting hand? There may also be musculoskeletal/repetitive risks for the data inputting hand/finger.

As an aside, there are now becoming available a range of what are termed 'wearable computers' and, if your application is suitable, you may wish to consider these.

Please contact me if you wish to talk over these issues - John.Ridd@btinternet.com

Posted By Richard
I've used a Psion Series 3, 3a and 3mx for about 7 years with no problems

Richard