First, make sure your Quick GPS is up to date ( although I'm not really sure just how effective quick gps is, I'm sure I've had a signal without updating in about the same amount of time)
On your MDA, go to Settings/Sytem/GPS.
Click on GPS and in Programs tab, set GPS program port to 'COM4'
Click Hardware tab, set GPS hardware port to '(None)', and set Baud rate to
'4800'.
Click Access tab, tick box for 'Manage GPS automatically (recommended)'
Load Tomtom and go into the GPS Receiver configure screen. Select Other NMEA GPS receiver. Next screen, slide GPS baud rate to 4800 if it isn't already at that. Click done. Next screen, highlight COM4 if it isn't already highlighted, then click on COM4 and it'll bring you to the next screen which shows your current GPS Status.
Make sure you are outside to get a signal. It can take anything from 2 minutes or longer. Mine rarely gets a signal before 2 minutes and sometimes much longer. Some people are very lucky and manage to get a signal within a few seconds, though I've no idea how they manage that.
Also, I've just replaced Navigator 6 with Navigator 7 which is essentially the same but with some different colours, splash screen and one or two additions in the change preferences menus. However, it has a new feature in the GPS Receiver screen which might be useful. It now has Built-in GPS receiver and there seems to be nothing to set after clicking on that. I'm going to go test it now, see if it's any faster or works at all.