I have Delorme's Topo USA, National Geographic's Topo! (Illinois and Wisconsin only), and ExpertGPS, and they each have their advantages and disadvantages.

The best topo map software I've seen is NG's Topo! State Series, but that comes on a state-by-state basis, and each state costs about $100, so I'd suspect it is too expensive for your needs. That said, it does provide the best map quality that I've seen, so that is why I have it for local use.

ExpertGPS is software (http://www.expertgps.com) that is designed to work with your GPS. It provides a place to store waypoints and routes, upload/download them from/to a GPS, and it also provides on-line USGS topo maps and aerial photos (from Terraserver I think - at no extra cost) on which you can mark the waypoints and routes. The newest version can supposedly also used scanned in maps, though I haven't played with that yet. It is really nice software for only $60. If nothing else, it is a fantastic tool for storing GPS waypoints for later use and for easy generation of routes using topo maps. I heartily recommend it. Keep in mind that the topo maps are ONLY available when connected on-line.

I'm not sure what to say about Delorme's Topo USA. I use Delormes Street Atlas USA ALL THE TIME, but I found the accuracy of Topo USA to be poor enought that I use ExpertGPS instead. As a matter of fact I don't even have Topo USA loaded on my PC anymore. It isn't a bad product, it is just that the scanned USGS topo maps available on ExpertGPS are so much more accurate and detailed.

Now if Delorme would merge Street Atlas USA and Topo USA, that would be very cool and I'd use that for sure. One of the things about Street Atlas USA that drives me nuts is that it won't provide UTM coordinates. Dumb!

If you do NOT have to run the software off-line (not on the internet), then I'd go with ExpertGPS. If you DO need to run the software off-line, then I'd go with Topo USA.

Get both if you can ... use Topo USA for visualizing the routes & running off-line, but then use ExpertGPS for managing waypoints and routes.

If you do get Topo USA, strongly consider getting the DVD version if possible. Swapping out CD's is a pain.