in C# I have a string I am writing to the outputstream of the response. After I save this document and open it in Notepad++ or WordPad I get nicely formatted line breaks where they are intended, when I open this document with the regular old windows notepad, I get one long text string with  square looking symbols where the line breaks should be.
Has anyone had any experience with this?
Yes - it means you're using
\n as the line break instead of
\r\n. Notepad only understands the latter.
Environment.NewLine suggested by others is fine if you want the platform default - but if you're serving from Mono and definitely want
\r\n, you should specify it explicitly.)