//按回车,焦点跳到密码文本框  
    private void txtUserName_KeyPress(object sender, KeyPressEventArgs e)
    {
        if (e.KeyChar == '\r')
        {
            txtPassword.Focus();
        }
    }
    //按回车,直接登陆  
    private void txtPassword_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == Keys.Return)
        {
            btnOK_Click(null,null);
        }
    }  

3.将窗体的AccptButton属性设置成你想要提交的那个按钮的名称就行了,不得不感叹微软实在很强!