Good site here:
http://www.pocketgpsworld.com/
or
http://www.pocketgpsworld.com/module...viewforum&f=93
Not sure re map upgrades, we run a 720 (not t) maps ok, we update speed cameras via above.
First thing to do is backup to PC, connect usb, open tomtom, drag big folder onto pc somewhere (takes a while). if it goes bellyup sometime you can copy it back and start again.