Right, this is a bit complex so I will be as gentle as I can.
I have a Tomtom ONE and also several PDA's. The Palm Tungsten T5, the Handspring Treo 650 and the HP (comapq) rz-1710.
The 1710 should have come with Michelin sat nav siftware but didn't. I have however got the sat nav receiver and cradle for it. The Treo is too big and clumsy to use for sat nav, and the Tungsten is the best option , but I do not have the receiver for it.
I do have the SD card for the tomtom ONE and an SD slot in the 1710. So, try it in there? No doesn';t work.
So, I downloaded the PDA version of tomtom for the 1710, unzipped it, unRAR'd it, unscrambled it, burned it onto the CD before installing the beaming partitioner to the hard drive (backup partition) and then sleezed the file onto a Zap disk ready to convert onto the SD card encryption program on my laptop. Oncve the Zap was made, all I had to do was to wiffle the SD card in WinRAR and load tomtom onto the wiffled SD card. Now, I can put the same card in the Tomtom ONE, the Palm Tungsten, The 1710 AND the Treo!!! Fantastic achievement even if I do say so myself. It doesn't work of course because most of the above is complete b ollocks, but at least it will put a smile on your face and make you feel a little less stressed by what you are doing.
So, try this method. I am sure it will help.