FileSystemWatcher

Here's a great little sample of FileSystemWatcher from Roy Osherove. Tank God for anonymous delegates :)

FileSystemWatcher watcher = new FileSystemWatcher("c:\\");

watcher.IncludeSubdirectories = true;
watcher.Changed+=delegate(object sender, FileSystemEventArgs e)
{
 string file = Path.GetFileName(e.FullPath);
 string dir = Path.GetDirectoryName(e.FullPath);

 ...
}
                                };
watcher.EnableRaisingEvents = true;