Isolated Storage in .NET
Isolated Storage is a virtual storage space on the file system that is exclusive to the user and assembly and/or AppDomain. With Isolated Storage, the user is absolved from knowing (or working with) absolute file paths, while still being able to work with the notion of directories, files and streams. This level of isolation makes Isolated Storage an ideal candidate for storing user/application profiles or user-specific configuration settings. With this setup, neither the application code nor the external world (other applications like explorer.exe) can actually see the physical files. Have a look at these articles to see good examples of how Isolated Storage can be used:
http://www.codeproject.com/useritems/appdata.asp
http://www.devcity.net/net/article.aspx?alias=isolatedstorage