该文原创，转载请注名出处。谢谢
配合VS2005里的文件上传控件，做了一个图片上传的例子，并把图片另存为70*70大小，如要判断图片大小和类型可做在页面代码之中。有兴趣的朋友可以去实现一下。很容易的。

/*
 * 类描述:该类主要作用于上传图片.
 * 
 * 作者:刘荣华
 * 创建日期:2006/11/21
 * 
 */
using System;
using System.Collections.Generic;
using System.Text;
using System.Web;
using System.Configuration;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI;
using System.Collections;
using System.Web.UI.HtmlControls;
using System.Data;

namespace UploadPicture
{
    public class CUploadPic
    {
        
        public bool Upload(FileUpload upLoadName,HttpServerUtility Server,out string ImgUrl)
        {
            bool flag = true;
            try
            {   
                /*读取保存原图的虚拟目录名称*/
                string DuumyActuallyPic = ConfigurationManager.AppSettings["ActuallyPic"];
                /*保存原图的路径*/
                string pathActuallyPic = Server.MapPath("../" + DuumyActuallyPic + "/");
                string fileName = upLoadName.FileName.Trim();
                string NewFileName = CreatFileName(fileName);
                string newPathActuallyPic = pathActuallyPic + NewFileName;

                /*保存原图*/
                upLoadName.SaveAs(newPathActuallyPic);
                CreateBreviaryPic(newPathActuallyPic,upLoadName.FileName,Server, out ImgUrl);
            }
            catch (Exception e)
            {
                flag = false;
                throw e;

            }
            return flag;
        }
        /// <summary>
        /// 产生缩略图
        /// </summary>
        /// <param name="picPath"></param>
        void CreateBreviaryPic(string picPath,string FileName,HttpServerUtility Server,out string ImgUrl)
        {
            string HostDomain = ConfigurationManager.AppSettings["Address"];
            /*读取保存缩略图的虚拟目录名称*/
            string DummyBreviaryPic = ConfigurationManager.AppSettings["BreviaryPic"];
            /*保存缩略图的路径*/
            string pathBreviaryPic = Server.MapPath("../" + DummyBreviaryPic + "/");
            string NewFileName = CreatFileName(FileName);

            string newPathBreviaryPic = pathBreviaryPic + NewFileName;

            System.Drawing.Image obj = System.Drawing.Image.FromFile(picPath);
            int imgHeight = obj.Height;
            int imgWidth = obj.Width;
            /**/
            if (imgHeight != 70)
            {
                imgHeight = 70;
            }
            if (imgWidth != 70)
            {
                imgWidth = 70;
            }

            System.Drawing.Image Breviary = obj.GetThumbnailImage(imgWidth, imgHeight, null, IntPtr.Zero);
            Breviary.Save(newPathBreviaryPic);

            obj.Dispose();
            Breviary.Dispose();
            /*生成的图片连接地址=网站域名+虚拟目录名+文件名*/
            ImgUrl = HostDomain + "/" + DummyBreviaryPic + "/" + NewFileName;
        }
        /// <summary>
        /// 生成唯一的图片名
        /// </summary>
        /// <param name="fileName"></param>
        /// <returns></returns>
        string CreatFileName(string fileName)
        {
            DateTime now = DateTime.Now;
            string str =
                now.Year.ToString() + "_"
                + now.Month.ToString() + "_"
                + now.Day.ToString() + "_"
                + now.Hour.ToString() + "_"
                + now.Minute.ToString() + "_"
                + now.Second.ToString() + "_"
                + fileName;
            return str;
        }
    }
}

然后在配置文件中加上

        <add key="Address" value="http://10.0.76.26"/>

    <!--保存原图的虚拟目录名称-->
    <add key="ActuallyPic" value="ActuallyGoodsImage"/>
    <!--保存缩略图的虚拟目录名称-->
    <add key="BreviaryPic" value="BreviaryImage"/>

就剩下最后一步，在IIS里对照上面的value值，建立你的虚拟目录，保存您的图片就OK
切记虚拟目录名称要和Value一样