Want to know Deploy ,setup and Stored data related some info

I have build a C# winform app including a database and deploy the app using the option publish.
I have setup this app and its working properly in my pc and any other pc.But what i really want to know is after setup when i am using this app and storing data where the data is being saved?I am using visual studio 2010.when publishing my app i have selected the sql server 2008 as the prerequisite. As a result after publishing the app there is a folder containing sql server 2008 is in my deploy directory and when i setup this app its install sql server first then the app. But when i setup this app it does not give me any option to change my setup directory. and if by default its being setup in the C drive then when i have to reinstall my windows again then will i lost all of my data of my app.If so then what is the way to avoid this problem? I want to keep all my data intact after reinstalling my windows.If my question is not clear enough then feel free to ask. I am really in a great problem with it so if anyone can help i with  suggestions.

Thanks in advance