I also have the 1:24K maps for my Garmin, but for my computer I use Maptechs Terrain Navigator Pro. It has every USGS map for your state that is interactive with aerial photos as well as Google Earth. You can mark waypoints, tracks, etc on it and download into your GPS and upload from your GPS on the topo or aerial maps. It's not cheap but you can sometimes score a good deal. I got mine off of eBay several years ago for a bit less and I think the non Pro version isn't bad.