I'm trying the same thing this year. I bought a Microsoft Surface 2. It will run an excel spread sheet I have for estimates. I have a portable printer, but haven't figured out how to go wireless with it yet. (I'm an older guy so technology isn't second nature for me) So, for now hooking up with a cord.
It's also really great for showing photos of our previous work in high definition. So far I've gotten great response.
Can you tell me more about the estimating form/program you are using.