Your Venture has 1MB of internal memory. Unfortunately, there is no space for downloading maps; that 1MB is mostly provided for the ability to save waypoints to your device.

The Vista HCx that BigAura has is very similar to the Venture HCx that I have. Both are eTrex units with a high sensitivity antenna ("H"), color screen ("C") and extra memory via a microSD card slot ("x"). By using the 1GB and greater cards you can purchase cheaply today, it becomes a very capable tool for storing multiple maps and countless routes/waypoints.

Since you already have your device....

As BigAura stated, go to garmin.com and download Basecamp. Just like Mapsource, this will allow you to create and manage waypoints and then upload them to your device. I believe the primary difference between the two is that Basecamp allows a simple process for transferring routes created on other sites (Bikely, ridewithgps, etc) to your device.

When you open up Basecamp or Mapsource, the basemap has limited detail; I'm sure you'll want something additional, but there's no point in purchasing an expensive Garmin map product just for the ability to manage waypoints. Go to gpsfiledepot.com and download a free map. I see that they have several quality maps for the Southeast (link). I downloaded the topo map for CA and find it to be just fine.

The Venture should be a fine tool for helping you find your way back in the event you become disoriented, as well as for navigating you from point to point. If you think you need a device with map storage and greater navigational capability (in addition to auto-routing), then you'll need to upgrade to an HCx, GPSMAP, Dakota, etc, but that's also another $250+ for the device plus city navigator maps.

You can also go here for more help. Let us know how it goes.