Something like the following perhaps?
public partial class Form1 : Form
{
private Timer t;
public Form1()
{
InitializeComponent();
t = new Timer();
t.Tick += new EventHandler(t_Tick);
t.Interval = 3000;
t.Enabled = true;
this.BackgroundImage = new Bitmap(@"C:\@Download\Images\Aero\FaireyFirefly.bmp");
}
void t_Tick(object sender, EventArgs e)
{
Font drawFont = new Font("Arial", 16);
SolidBrush drawBrush = new SolidBrush(Color.Black);
PointF drawPoint = new PointF(10.0F, 10.0F);
Graphics g = this.CreateGraphics();
String legend = DateTime.Now.ToLongTimeString();
Rectangle r = new Rectangle(10,10,100,30);
Invalidate(r);
Update();
g.DrawString(legend, drawFont, drawBrush, drawPoint);
g.Dispose();
}
}