/// <summary>
		/// 
		/// 
		/// </summary>
		/// <param name="sourceDir">source directory</param>
		/// <param name="targetDir">target directory</param>
		/// <param name="targetDir">file type (mp3)</param>
		static void Mp3FileCopy(string sourceDir, string targetDir, string fileType)
		{
			try
			{
				foreach (string d in Directory.GetDirectories(sourceDir))
				{
					foreach (string f in Directory.GetFiles(d, fileType))
					{
						File.Copy(f, 
							targetDir + "\\" + new FileInfo(f).Name, 
							false);
					}

					Mp3FileCopy(d, targetDir, fileType);
				}
			}
			catch (System.Exception excpt)
			{
				Console.WriteLine(excpt.Message);
			}
		}

Mp3FileCopy("d:\\download", "d:\\mp3test", "*.mp3");