@migo PocketPC2k2, with WriteSHIELD
I am using a PocketPC (upgraded to 2002) @migo PD-600C from UR There Int. They were pretty cheap, because they have problems (flakey batteries, etc.) But, they do have a built-in PCMCIA-card slot.
Yes, I have to press pretty firmly to register a tap. I think this factor probably does have an impact on achievable WPM.
I also use a WriteSHIELD screen protector. I'll never use a PDA again without some kind of screen protector. WriteSHIELD (note, not WriteRight) work great: they come as a 3-pack, and my first one hasn't scratched yet in the couple of months I've been using it. I highly recommend them, even if they are kind of expensive at ~$US30. You get 10% if you follow the link above.
If that's too much for you, make your own from a sheet of over-head transparency film (if you go to a copy shop, you can buy a single sheet for like $US.20 and make 8 protectors). I used these for quite a while: when they are too scratched, replace them!
-Richard L. Owens