If you click on the East,West, South & Shannon links on that page it shows you the coverage of the DVDs. Pretty poor. The west one is the only comprehensive one of them. The south does Kerry and some of Cork. The Shannon one obviously just does along the Shannon. The East one does down Wicklow and a line through Weford and Waterford.

At that rate it'll take at least 10 DVDs to do the trick. They are PC compatible only, but the contouring stuff looks fun. You can also export waypoints, which is nice. I might try the Mayo/Galway one out.