You can transfer your topomaps on to your Garmin using Mapsource (= Garmin software, I know there's some new software out, called basecamp, also made by and for Garmin, but I haven't used it much, so I don't know it yet).
First you'll have to "unlock" your topo maps on your pc, which means entering a 25 digit code if I"m not mistaking, once unlocked you can select the sections of the topomap that you need and transfer them to your GPS unit.
Once that you've transfered the topomaps on to your Garmin you will have to select "hide city navigator maps" in the map menu, because the city navigator maps are always on top of the topo maps, once you hide the city navigator maps, the topo maps are automatically shown on the GPS screen.
I love my Map 60 CSx, use it for mountainbiking and hiking, and also used it for motorcycling (back in the days when I still owned my Kawasaki ZX9R Ninja ...
).