has any of you guys, tried the < navionics dvd's > I thought i might buy one and use it in my computer, on these cold winter days and look at some spots to fish on cumberland and dale hollow. it says on the cover 10,000 lakes. how many lakes from ky i wonder. priced for 20 bucks. shows the lake bottom in 3d,has any of you guys bought one. did you like it? or is it a wast of 20 bucks.