using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;

public class Test
{
	public static void Main()
	{
		var pattern = @"(Project\(""{[\w-]*}""\) = "")[^\s""]*("", "")[^\s""]*("", ""{[\w-]*}"")";
		var inLine = "Project(\"{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}\") = \"Common\", \"Libraries\\Common\\Common.csproj\", \"{91197577-34B9-4D46-B3FE-A8589D4380B1}\"";
		var replaced = Regex.Replace(inLine, pattern, @"${1}Blah${2}..\Core\Libraries\Blah\Blah.csproj$3");
	 	Console.WriteLine(replaced);
	}
}