this was the response I've just got back from tom tom - and yes its terrible
Discussion Thread
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Response (Celeste H. (UK)) - 15/11/2006 02.13 PM
Dear Sir,
Thank you for contacting TomTom Customer Support.
The HP iPAQ hx4700 is compatible with Navigator 3 and Navigator 5. There =
is no upgrade version.
With best regards,
The TomTom Customer Support Team
http://www.tomtom.com
utter crap response.