static void Copy(Stream inStream, Stream outStream)
{
    Copy(inStream, outStream, 1024 * 1024);
}

static void Copy(Stream inStream,Stream outStream,int bufferSize)
{
    byte[] bytes = new byte[bufferSize];
    int len;
    while ((len = inStream.Read(bytes, 0, bytes.Length)) > 0)
    {
        outStream.Write(bytes, 0, len);
    }
}

using (Stream inStream = new FileStream(@"d:\temp\DevCpp.zip",FileMode.Open))
using (Stream outStream = new FileStream(@"d:\temp\1.zip", FileMode.Create))
{
    Copy(inStream, outStream);
}

文件下载器：

WebRequest req = WebRequest.Create("http://www.baidu.com/img/bd_logo1.png");
using (WebResponse res = req.GetResponse())
using (Stream inStream = res.GetResponseStream())
using(Stream outStream = new FileStream(@"d:\temp\2.png",FileMode.Create))
{
    //inStream.CopyTo(
    Console.WriteLine(inStream.GetType());//Object o = new Person();
    //Copy(inStream, outStream);
    inStream.CopyTo(outStream);
}

stream