I have been doing a fair bit of research on these questions myself. On the TTN6/Axim x5 issue, TomTom themselves will only reply with a stock answer - the one I eventually got was:
"With reference to your e-mail and reference to our second line technical department, please note we do not support the use on the Axim X5. We have tested it on the actual specifications of the Axim X5 by default and found it to be incompatible. We have a number of compatible PDA's listed on our website."
It is quite clear though, from reading these boards, that the Axim x5 is certainly capable of running TTN6. It does need a fix - see another thread here
Tomtom 6 Maps Not found.
I haven't tried a 2GB SD card yet myself but the limitations are dealt with here:
SD Card size maximum. I have had some curious messages on the Axim relating to SD cards and led me into finding a veritable can of worms. There is a whole subsite linked to Aximsite on this issue albeit no info on the latest SD cards - see
http://sdprob.aximsite.com/. Hope this helps - at least you can see you are not alone!
