using System.Diagnostics; //需要添加这行引用,关于线程的
private void button1_Click(object sender, EventArgs e)
{
    string path = @"C:\Program Files\Tencent\QQ\QQ.exe";    //这个path就是要调用的exe程序的绝对路径
    System.Diagnostics.Process process = new System.Diagnostics.Process();
    process.StartInfo.FileName = "qq.exe";
    process.StartInfo.WorkingDirectory = path;
    process.StartInfo.CreateNoWindow =true ;
    process.Start();
    if (process.HasExited)
    {
          MessageBox.Show("complete");
    }
} 
还有其它的可以参考下面的网址
参考资料:http://hi.baidu.com/d369608w/blog/item/6358c752ed90600b0df3e303.html