Deep copy of objects in C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using HAKGERSoft;
using NUnit.Framework;
using System.Reflection;
using System.ComponentModel;

namespace HAKGERSoft {

    public class Differ {

        public static void Check(object a,object b){
            if(a==null && b==null)
                return;
            Type t1=a.GetType();
            Type t2=b.GetType();
            if(t1!=t2) {
                Throw("Types are not same, type(1)={0}, types(2)={1}",t1.ToString(),t2.ToString());
            }
            else if(t1.IsValueType) {
                if(!a.Equals(b)) {
                    Throw("Value type not same!");
                    return;
                }
            }
            else if(a is string) {
                if((string)a != (string)b)
                    Throw("Value diff");
            }
            else if(t1.IsClass) {
                if(object.ReferenceEquals(a,b))
                    Throw("Reference equals");
                FieldInfo[] fields=t1.GetFields(BindingFlags.Public|BindingFlags.NonPublic|BindingFlags.Instance);
                foreach(FieldInfo field in fields) {
                    object o1=field.GetValue(a);
                    object o2=field.GetValue(b);
                    Check(o1,o2);
                }
            }
        }

        static void Throw(string format,params object[] args){
            Throw(string.Format(format,args));
        }

        static void Throw(string message){
            throw new ArgumentException(message);
        }


    }
}