In reply to MG:
There are quite a lot of options:
Best one and the most expensive is TopoSwiss in all it's variants.
For the Alps there's simply nothing better, however the price is prohibitive. Expect to pay north of 300EUR - so probably more than the GPS unit itself is worth.
Another possibility is the OpenStreetMap project maps: these are community created open source maps freely available, but normally with a bit lower quality of course, especially compared to SwissTopo products. However, you get this free and there's a website dedicated to Alps:
http://www.wanderreitkarte.de/garmin_de.php where you can get the maps for the region you are interested in.
In general on Garmin website you will find all the maps (ie for France
http://www.garmin.com/fr/maps/cartes-topographiques/cartes-numeriques/ )
All in all, I find dedicated GPS and dedicated map software for PC far superior to the touch interfaces and various mobile alternatives: both for planning as well as for the "on the trail" as well. I am guessing you already researched the subject, but there are a few things to look for in GPS maps: if the maps are routable, if they are in 3D etc - all to be considered when making selection. The prices of official maps are horrible, but you can - depending on the region - get some great alternatives. For example in Spain we have a few projects (for Pyrenees and Picos de Europa notably) of independent developers using their own research and official state data that are superior to official Garmin maps and cost none or very little (think 5EUR) money.
With a bit of dedication and tinkering you can make the Garmin GPS unit work for you for little money.
Cheers
RS