If you want to upgrade to a better model
The Go920 allows map corrections and allows you to share those connections with other TomTom users. It has 4 gig of memory and a memory card slot, comes with North American and Western Europe maps. I think the 720 is similar but does not have 4 gig of memory. These are not the latest models and can still be found at reasonable prices.
To share more information on TomTom, try:
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We recently purchased a Go920 to replace our older Magellan 3050T and overall like the TomTom better, especially the ability customize it and to add third party software to add different features. We use ours on a motorcycle and having a event logger really is nice as afterwards I can have the created itn file used on Google Earth and review where we have been, I know it's backwards, most people use the gps to find where they want to go and we use it mostly to show us where we were as we explore many different roads and many times see things but forget how we got there.