Okay, to the laptop software question.
If you want to continue to use Garmin maps you can consider Garmin's Mobile PC. It has all the features you have in the iQue plus more. But it has a different interface. It's more like the interface on Garmin's Nuvi handheld devices. You can easily transfer tracks and routes and waypoints between Mobile PC and MapSource. In addition to all the standard routing things, Mobile PC has text-to-speech so it speaks the names of streets when telling you to turn.
You probably already know that you can use MapSource to view routes, tracks and waypoints in Google Earth (under the View menu, select "View in Google Earth"). I don't think there are any laptop navigation programs that will use KML files directly but there are utilities out there to translate between KML and GPX files. MapSource knows how to read GPX files and can transfer the resulting routes, waypoints and tracks to Mobile PC.
You can check out the discussions about Mobile PC in the
Garmin Mobile PC part of this forum.
EDIT: Ooops, missed your question about using the City Navigator maps that you already own. Nope, they won't do you any good with anything else. None of the non-Garmin laptop navigation programs will use them. The good news is that for less than the price of a City Navigator update you can get Garmin's Mobile PC and it comes with the latest version of City Navigator North America 2009 already loaded.
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