I would stick to the IT stuff and get together with an experienced AV company if you value your reputation and your clients. Unfortunately you need to charge about 50% less than usual on the things that you are unfamiliar with. Your client shouldn't be paying for your learning curve. Regular trim out should be billed at whatever you bill but programming should be discounted as it's going to take you a long time to get right.

BTW...how is it that you only have 9 tv/phone runs in a 7000sqft. house? Something is wrong there man! It's really scary that you have been in business for 5 years and are asking this question. Obviously it needed to be asked...but, the owner of the company should get some professional training before you get yourself in too deep dude!