How to remove illegal characters from path and filenames?

Question

I need a robust and simple way to remove illegal path and file characters from a simple string. I\'ve used the below code but it doesn\'t seem to do anything, what am I miss

Answer 1

public static bool IsValidFilename(string testName)
{
    return !new Regex("[" + Regex.Escape(new String(System.IO.Path.GetInvalidFileNameChars())) + "]").IsMatch(testName);
}