Just had a quick play and i have no problem with just doing
Code:
		private void button1_MouseLeave(object sender, System.EventArgs e)
		{
			this.button1.BackColor = System.Drawing.Color.DarkBlue;
		}

		private void button1_MouseEnter(object sender, System.EventArgs e)
		{
			this.button1.BackColor = System.Drawing.Color.Black;
		}