Tim Mackey's Weblog

public static char GetRandomLowerCaseCharacter(int seed)
{
   return ((char) ( (short) 'a' + new Random(seed).Next(26)));
}

public static char GetRandomUpperCaseCharacter(int seed)
{
   return ((char) ( (short) 'A' + new Random(seed).Next(26)));
}

If you call the above methods straight after each other with the same seed, you may get the same value on a fast processor.  It is a good reason to pass in a different seed value for operations that will be done in quick succession.  E.g. use DateTime.Now.Seconds for one operation and then use Minutes or Hour or Milliseconds for the next ones.