As mentioned, you need the CDs with maps to route or have more maps than the basic base map included with the unit. It is 100% "possible' to make your own maps, but downloading them is nearly impossible. The only way to download a map is for someone to have created their own and host it somewhere that you could find it. Pretty small odds-
Also, you may want to re-think the 2GB chip. The Garmin can handle the chip, but won't run very fast. The best be is to only load the topo/map data for the area of interest and leave the rest off. You can load 1/2 of the mountain west if you so desired, so the area of interest can be much larger than your specific hike or hunting area, just don't think you'll get optimum performance with the entire continent loaded.
If you decide to get topo maps, the average topo grom Garmin is 1;1,000,000 scale, or 90M resolution. OK for basic stuff, but not really good by most standards. They also sell National Parks Topo maps at 1:24,000 scale, MUCH better, but you have to be near a National Park to get coverage.
Again, it's possible to make your own from scratch and load them onto the GPS, but not very newb-friendly. For GPS newbs or GIS/Mapping newbs. Google searches can get you started if you really want to pursue it.