进程是否运行判断

如何判断进程中存在*.exe若不存在则加载，存在则提示用户该进程已经运行！
c#实现！

--------------------编程问答--------------------         Process[] pco=Process.GetProcesses();
            foreach (Process p in pco)
            {
                if (p.p.ProcessName == "你想检查的进程")
                {
                }

            } --------------------编程问答-------------------- Process.GetProcessesByName("ProcessName"); --------------------编程问答-------------------- 你写的程序得不到我要的结果
我改了下还是有问题

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Diagnostics;
using System.Windows.Forms;
using System.Diagnostics;

namespace WindowsApplication3
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            Process[] pco = Process.GetProcesses();
            foreach (Process p in pco)
            {
                if (p.ProcessName == "notepad.exe")
                {
                    MessageBox.Show("已经存在一个进程了");
                    break;
                }
                else
                {
                    System.Diagnostics.Process.Start("notepad.exe");
                    break;
                }
            }
        }
    }
}

是不是哪写错了？

--------------------编程问答-------------------- 多了个exe --------------------编程问答-------------------- 还是不行啊！ --------------------编程问答-------------------- using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Diagnostics;
using System.Windows.Forms;
using System.Diagnostics;
using System.Threading;

namespace WindowsApplication3
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            bool isFind = false;
            Process[] process = Process.GetProcesses();
            foreach (Process p in process)
            {
                if (p.ProcessName == "notepad")
                {
                    label1.Text = "已经运行了一个notepad.exe";
                    isFind = true;
                    break;
                }
            }
            if (isFind == false)
                System.Diagnostics.Process.Start("notepad.exe");
        }
    }
}
不好意思，原来程序有问题。
现在OK了!
谢谢大伙啦！

补充：.NET技术 ,  C#