I'ld like to know if any of you uses their PDA as their GTD 'trusted system'.
Is it really possible to keep all projects under control by just using Windows Mobile or Palm OS?

There are only about 15 lines in landscape and about 25 lines in portrait mode as far as I know.
And that's the case with Win 320 x 240 AND 640 x 480 AND Palm OS 4 and 5 with 480 x 320, isn't it?
(Always just a little window the size of an index card.)

My aim:
I would like to use a PDA (with built in keyboard = faster than soft-keyboard or graffiti) to write down all projects and all the steps to take.
Then mark some items as next actions / @phone / @errands etc.
Then get them automatically into the appropriate lists.

Example:

Repair bike
> Buy tyres
>> Types
>>> ABC
>>> XYZ
>> Call bike shop
>>> Ask for prices

If you copy 'Ask for prices' to an @phone list, it doesn't make sense without
'Types', 'ABC', 'XYZ'.

The other option would be:
Repaire bike > Buy tyres
Repaire bike > Buy tyres > Types
Repaire bike > Buy tyres > Types > ABC
Repaire bike > Buy tyres > Types > XYZ
Repaire bike > Buy tyres > Call Bike Shop
Repaire bike > Buy tyres > Call Bike Shop > Ask for prices
...but I guess that doesn't quite work, either.

And what do you do if for exampel your labeler has broken down and you need a new one?
You get another 'Ask for prices' - this time it doesn't work without 'DYMO' or 'Casio'.

IS there any PDA software at all which lets you keep everything in view?
Out of sight is out of mind. And back into psychic RAM :(

In other words:
Does anyone of you really use their PDA as a trusted system that delivers all?
And if you do, what drill do you have to follow?