I got the Bluetooth Thinkoutside Sierra Keyboard (five rows) for these reasons...
1) Can use it when I hookup the Axim x51v to my 50" LCD TV via VGA out, int True VGA mode. I can then sit on the sofa about 12 feet away.
2) At home I regularly use the Axim x5v with a 19" LCD monitor (it sits in a corner in b'fst area) and I can use it using Bluetooth keyboard and Bluetooth mouse. It's my substitute for a laptop computer for basic computing needs.
The #2, #3 above were my requirements, so I had to get a Bluetooth one. I can still use it with the Axim next to the keyboard and mouse.
BTW, this keyboard and mouse is also compatible with a Mac or PC (have not tried that yet) if they have a Bluetooth.
The disadvantage is I cannot use it on an airplane or with an IR only PDA (I have a iPaq 3850)