The 3800 series have a built in MMC/SD Slot on the top, it also has 16bit color, it fixed the problem from the 37xx/36xx series where if more then 1 button was press simotaniously, it would not be recognized (bad for games), the 3800 also has a bigger battery capacity and a fixed stylus silo so the stylus will not get jammed. Another minor thing is that the speaker is moved to the top so that when you put you finger on the joypad, it dosen't distort the sound on the 3800 unlike the 37/36xx where the speaker waas on the d-pad. And majorly, the dust issue was supposedly fix where dust would leak into the pack of the backlight and glowing specks of dust would appear when you use the ipaq. This mainly happened in the 36/37xx series and a few cases in the 38xx. I hope that helps
Think about a HP Jornada 568/567, those look pretty good.