I am trying to find the best computer mapping program.  I want something that has detailed maps of lakes and even 3D maps.  I want something I can run on my desktop of laptop and download directly into a GPS system.

two words:Navionics chips

Get yourself a good graph, and you can buy chips for lakes all over the country for the unit.  Most if not all pro anglers use the chips from what I understand.  Much easier than the paper maps, and you don't have to download stuff from your puter.  Just load the chip and go.

This is not going to help you unless you are fishing Ky or Barkley Lakes.  A couple years ago a company call Kentucky HYDRO GRAFX complety remapped Ky and Barkley Lakes using side scan sonar.  The difference between their scans and the old maps when the lake was made is huge.

If you are fishing Ky or Barkley go to their web side and get the section of the lake you are insterested   in.  Load the info into you GPS and you are ready to go.