Thanks for the clarification, Potski. Based on that information, you have two options that I'm comfortable will work.
Option One is Garmin Mobile PC (Europe). If you make sure to get the latest version it should come with the City Navigator 2010 maps preloaded (insist on it). My recommendation would be to buy the version that comes bundled with a GPS receiver, either the GPS20x (USB connection) or the GPS10x (Bluetooth connection). This will allow you to upgrade Mobile PC to new versions of City Navigator Europe as they are released. Or you can subscribe to NuMaps lifetime updates that you can download approximately quarterly.
Mobile PC will allow you to record tracks and transfer them to Mapsource so you can continue to create your own custom routes just as you are doing now.
You can transfer "Favorites" (waypoints) and routes and tracks both directions between Mobile PC and Mapsource. So if you have any Favorites or My Locations or whatever the Zumo calls them, you can transfer them from the Zumo to Mapsource and then to Mobile PC rather than having to re-enter them manually.
I think the Zumo interface is very similar to the Nuvi so you should find the interface in Mobile PC quite familiar.
Option Two is Microsoft AutoRoute 2010. In the 2010 version of Streets&Trips and AutoRoute, Microsoft has introduce the ability to import and export GPX files. That means you can transfer track files between Mapsource and AutoRoute using GPX files.
There are limitations in how much detail AutoRoute transfers in the GPX files. For instance, it does not do the time stamp for trackpoints properly when importing and exporting tracks. There are a couple of threads in the Streets&Trips section here with extensive analysis and explanations of using GPX files with the 2010 version. It will apply to AutoRoute.
I believe Garmin and Microsoft both use Navteq maps for their European coverage, just as they do for North America, so maps might not be a deciding point between the two options if you need to stick with easy-to-use preloaded maps. However...
One advantage to Garmin on the mapping issue is that there are myriad options available for Garmin products if you aren't satisfied with Garmin's City Navigator maps and are prepared to do a little research and learning.
First, Garmin has topographical maps for many parts of the world. They have them for France but I don't see any for Spain.
If you want more detail and are making your own "routes" anyway, you can probably find free topographical maps with great detail on the backroads for most of the areas you travel in western Europe and many parts of eastern Europe. It requires a bit of learning to incorporate them into Mapsource and then into Mobile PC but if you're already playing around with track files to create your own routes, it's no more difficult to understand.
Reliability will be a function of your laptop or netbook computer.
There is a cheaper alternative to either of the above (free) called nRoute from Garmin. If you already had a GPS receiver I would suggest you play with it to see if you like using a laptop for navigation (doing so has issues unrelated to which navigation software you choose, such as mounting, screen visibility in daylight and more). But it will be very limited. You can use it with your existing CN Europe 2008 maps but not with any newer City Navigator maps. They have changed to a format that nRoute can't use and nRoute hasn't been supported by Garmin for years.
I hope that gives you some things to think about. Check out the Garmin Mobile PC and Streets & Trips reviews and other discussions of interest in their sections on Laptop GPS World.
...ken...