[Bro's lacky]

Hello......I need your expert help please. My brother has opened a shop, and asked me if I would keep his books up together !! He says he has not got the time and it is easy! Well it might be easy to him, as he never does it.
He has been open since Nov 07 and last week dropped off his "paperwork" for me to get started. It was in a box, no paid or unpaid, bank stats that dont add up, but the worse thing is he is missing payment dates, because he files everything in this "box". Suppliers are threaterning to stop dealing with him, and red bills everywhere.
He is a great bloke and is doing really well in the shop, but his financial side is terrible. He is fine with pc's and I was wondering if there is a excel program that I can put all this on, then he will be able to see when things are due?
Im not a user of excel but I should be able to enter things on there, its the timescale of payments, or non-payments that is a big problem. Any help would be gratefully received.