Reports with actual cost of showing billable and un billable and comparing with what has been charged out instantly would make a business manager life much easier. Knowing at any time what is left on Purchase Order and comparing with what has been from Estimate and invoiced all makes much easier for a business manager or business owners. Using excel is ok but it requires manual processing and not integrated with your accounting system .
Any one going thorough this issues, we have at Cosmic Innovations have tools that can help you.
also have a look at our video at
http://cosmicinnovations.com/Video-CosmicTimesheet/