RE: check out my nifty map!
skidmark, I don't have a GPS so I wouldn't know how to do it with one. What I did was opened to sessions of internet explorer. and put both of them on mapmart.com. I moved to the location of my hunting site. This site uses certain map positions and size that it will default to if your just click to zoom in. Since the topo and the aerial defaulted to the same size, I downloaded them both.
Next is where photoshop comes into play. I took one image and placed it onto of the other one (the topo is on top) and made it 34% visible thereby letting the other bleed through and seeing details on both. There are more programs than just photoshop that do this but I'm not sure what other ones there are by name.