The problem is that Tomtom activated some sophisticated user-anonymous-data-sourced road additions in recent maps. This greatly grew the map sizes with all the newly added roads. And now many of the maps don't fit in the devices they were intended for. Further, Tomtom HOME gets all confused with insufficient space, and reports all sorts of incorrect errors that don't say "insufficient space"
So now onto solving the problem.
adiholl - the North_America_2GB map still fits if you clean up the internal Tomtom memory. First do
this backup, then format the internal Tomtom memory. Then have Home install the latest application 8.351 (you may need update the application a few times). Don't install anything else like voices yet. Once you have the latest application, go to add traffic/voices -> items on my computer. And add in your latest map. Once added, go and add you desired computer voice and all the other updates you want. You probably can only fit one computer voice. And to answer your other question - maps are serial-number locked, you can put them on any SD, internal, etc, as they'll only work on the Tomtom serial number they were purchased for.
stumpy87, map activation codes are automatically installed via Tomtom HOME, you no longer need to enter them manually like you had to years ago. One of the occasional symptoms of running out of space is that HOME sometimes errors before it can install the activation code. The resolution steps are
here, although if you have no map you may need to call Tomtom support to get a map reactivated for you. It's a bit more complicated as the Europe map is really big and there's no room to spare, but it's a common request that they'll have a ready answer for. Judging from the posts in this forum - expect long hold times.