I just installed a TomTom Navigator 6.010 on my N73. First of all it can't find a GPS signal and during the installation it asked for either a tomtom GSP or other bluetooth GSP. I was told be the person I bought it off that it does not need one. Any reason why GSP wouldn't work??? If I get an external GPS will that solve the problem? Pleas help if you can.
It is my experience that any GPS receiver works fine with the N73 and the price difference is not big. However, after having used several receivers, I strongly recommend the Nokia LD-3W.
Most receivers must be switched off manually and, if you don't, battery will generally drain within one night. When you disconnect the Nokia LD-3W, after having used it for navigation purposes, it automatically goes into standby mode. It can then stay in standby mode for several days without recharging.
Big advantage is you never need a cold fix, as it keeps the active coordinates. So, by leaving it in the car with a permanent power connection, you never have to switch-on or -off the receiver and it almost immediately has a fix when connecting the N73 to the receiver.
Do a search on eBay for Bluetooth GPS receivers. The BT-77 is extremely good value for money nowadays and can track up to 16 satellites. The battery life is amazing too. Mine lasts for a few days between top ups and it can even be charged up via USB (adapter included).
As Rob says, V3 Firmware is almost essential as it fixes the little bugs the N73 had with Bluetooth.