I am monitoring the development of Tablet PCs with interest. They have taken a long time to establish any kind of market share, but the pace of development does now seem to be accelerating.
I have been looking at various options myself and agree with most opinions that the PDA form factor is just too small (I have an iPaq hx4700). More and more software is being released with Tablet PCs in mind and I am about to start using a Fujitsu ST4121 (10" screen). They seem to be one of the first Tablet PCs used seriously in aviation (try googling aviation and ST4121).
If anyone is interested I have a couple more of these I was going to stick on ebay. Brought out a couple of years ago but with apparently the best sunlight readable screen on the market (same as the current ST5000 series). Google will provide the tech specs.
When I can buy a thin tablet with a 10" sunlight readable display and large FLASH drive for < £1000 then I will give it very serious consideration!
It is possible, there are suitable 2nd hand tablets out there (like these ones!). Hmm, this post has turned into a bit of a plug - wasn't supposed to be. Just excited about my new toy and thought others might want to get a cheap option (PM me if you do).
Anyway I'll post an update once I've had a chance to put it through it's paces.