Of course that exist that is thousand times written, however, not small, so doing that yourself needs expirience because you are busy in at least three different environments.
One of the presentation layers (forms, Silverlight, WPF by instance)
Net for Applications (in fact for office)
The database which can be any database and have different solution methods.
When you want to do it, you can start with using Net for Applications, which have controls for Excel, Word, InfoPath, Visio and Outlook.
Success
Cor
