Church software advice - my first attempt at a "real" program.

I have mentioned before that I am desperately trying to break into C# and programming.  I have several courses under my belt and am working as fast and as furious to gain knowledge that a full time employed, father of two, college student can (oh ya, Im married also).

I have decided to try and develop a few actual progams that I can put on my resume' site -- I have a church who would like me to develop a type of member software that will store tithes and offerings, allow pulling from the dbase, and would like to be able to port the info into a Word doc for printing and reporting (not to mention different calculations on the funds -- adding single users, adding monthly totals, annual totals, etc.) ---

My thought is that this might be easier for me and them if I make this web based using C# and ASP --- I was just hoping for some advice on where and how to start.  How to plan the project, anything that will start building me some experience and help me in the goings on of this project.

--I also just can't help shake the idea that all this could be done just as easily in a Spreadsheet!  Obviously I dont want it to be that way, but I dont want to waste these people's time if they could do it easier and better in Excel.  What do you guys think of that?  What is the advantage of a tailored piece of software over a spreadsheet in this case?