Make the DM Tools program as simple as possible. Many DMs like D&D table-top games partly because they enjoy the break from using a computer. So the more intuitive it is and the less like a computer program it is the better.

What I've noticed with most computer gaming "aids" for D&D is that they just make the game more cumbersome than it has to be. If the Tools can be so simple that you can just point and click without having to spend time figuring out how to use the program, then I think more people will use it.