In theory, very safe, as the config file is tied to the ASP.NET runtime. In
reality, who knows? Hackers are going to look for this type of information
and it is open text (in the 1.0/1.1 framework, at least). I would encrypt;
there are some good articles on MSDN for using the machine key to encrypt
secrets. In fact, the http://msdn.microsoft.com/architecture site has a
treasure trove of books on a variety of topics.

Signature
Gregory A. Beamer
MVP; MCP: +I, SE, SD, DBA
**********************************************************************
Think Outside the Box!
**********************************************************************
> Just wondering how safe it is to include sensitive information such as a
> database connection string in web.config.