Thanks for pointing me in the good direction. I was under the impression that 2GB was the max size for a card that could be used in the Go730. Probably last time I tried it it was true (bootloader version and whatnot). On the other hand, good luck finding a 4GB card in store .
So I got myself an 8 GB microSD card, put the map on it, activated it and all is good.
Thanks again !

"Agreed, I think you've "made room" by deleting something crucial"

Car pictures, unused voices and the cspeech file for Texas ?

"Maybe you removed something you shouldn't have ..."

Maybe...
Maybe...