Pick a brand, then become as familiar as you can with it. Take their training, develop vendor relationships, just like YOSC said. Start with your own shop, then start deploying them to clients. This will make you intimately familiar with the product, and able to offer a good-for-your-client and profitable-for-you solution. When I went through this several years ago, I chose SonicWall - are they the best? I have no idea, but they are one of the top players and over time, I've learned how to do most things with their units. We've got about 130 in the field right now, so the recurring revenue on the licensing and replacement units shows up very nicely in our income statement.