Oh, and just for completeness, here is hoe to get all 3 at once. I've changed it to get anything that is not white space.
string test = " 123 456other stuff 789";
Regex re = new Regex("^\\s*(\\S{3})\\s*(\\S{3}).*(\\S{3})$");
Match match = re.Match(test);
System.Console.WriteLine("First three = " + match.Groups[1].ToString());
System.Console.WriteLine("4, 5, and 6 = " + match.Groups[2].ToString());
System.Console.WriteLine("last three = " + match.Groups[3].ToString());
[red]"... isn't sanity really just a one trick pony anyway?! I mean, all you get is one trick, rational thinking, but when you are good and crazy, oooh, oooh, oooh, the sky is the limit!" - The Tick[/red]