Can I use .NET (and ADO.NET)for small program development?

Question

Please excuse the newbie question, but I would like to develop a small business program for a family business. It's for a childcare center and they really don't like the program they're currently using not to mention the poor support. I'm currently learning C# from some books but I still don't know if there is a small scale database feature available to me without additional cost beyond Visual Studio .NET. I once did a school project with an early version of Access, but I may want to market this product if it turns out good and so that is another consideration. I don't know which tools to learn to best produce this program. I would appreciate some guidance before I get too deep in the wrong direction. Thanks.