I have a Dell Axim X51 PDA that is not shabby by PDA standards.
Hm, that's weird. I just wrote an opposite post. I have a, I dunno, 1999 or 2000 Axim X5. The predecessor to your X51. What an awful, horribly outdated thing I remember it being. Funny though, that after using the iPhone for the last eight months or whatever its been, and realizing the Apple device wasn't capable of doing any of the few functions it does have 100%, I pulled the Axim back out to get through my work day, fired it up, and was surprised to remember just how useful and easy it is to use. The thing isn't noticably any slower than the iphone, but does everything, plays everything, holds more data, is expandable, lasts longer on a charge, has removable, spare, and high capacity batteries, 100% syncronization, total disk-access freedom, Cut/Copy/paste, has Wifi, Compact Flash, SD card slots, same slow internet, a voice recorder, can download and save off internet (not just the web) & email (& not just text & jpegs), infrared, bluetooth, a couple external keyboards, a finger-touchscreen, plus a stylus if desired (say for sketching), etc, blah blah blah... and yet, clean, simple and easy, and hadn't crashed in years. If I'd spent $250 on a cellphone Compact Flash card instead of $500 on the iPhone, this thing could be a cellphone too. Makes my iPhone look like a dumbed-down kids toy, and about as useful as one.
Since I found myself using the Axim for file transfers, Calendar, and To-Do lists, I now only use the iPhone as an overpriced cellphone, and a counterweight to my otherwise cockeyed belt.
One of these days my pants are going to give out, and I'll be standing pantsless in the middle of the office. I know it. And when they do, I'm just going to leave them lay there, and go buy a rotary phone.