Generics Issues

I've never really used Generics before so I'm still struggling with it.
What I think I want to do, is have a method that returns List;. I can return the list ok, and I can use Activator to create new T objects. The only problem is that my test requires some boxing, which is what I want to avoid. I'm wondering if the boxing will disappear in a real world example.

test code




using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;

namespace GenericsTest
{
class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Test 1");
        Factory fact = new Factory();
        List<obint>; test1 = fact.GetList<obint>();
        foreach (ObInt item in test1)
        {
            Console.WriteLine(item.Data);
        }

        Console.WriteLine("\nTest Two");
        List<int> test2 = new List<int>();
        test2.Add(1);
        test2.Add(2);
        test2.Add(3);
        foreach (int item in test2)
        {
            Console.WriteLine(item);
        }

        Console.WriteLine("Done, hit anykey");
        Console.Read();

    }
}

//The Goal is to see if I can return a Generic list
public class Factory
{
    public List<t> GetList<t>() where T : IObject
    {
        List<t> list = new List<t>();

        T tmp = Activator.CreateInstance<t>();
        tmp.Add(5);

        list.Add(tmp);

        return list;
    }
}

public interface IObject
{
    void Add(object item);
}

public class ObInt : IObject
{
    protected int _data;
    public int Data
    {
        get { return _data; }
        set { _data = value; }
    }

    public ObInt(int data)
    {
        _data = data;
    }
    public ObInt() { }

    public void Add(object item)
    {
        _data = (int)item;
    }

}

public class ObString: IObject
{
    protected string _data;
    public string Data
    {
        get { return _data; }
        set { _data = value; }
    }

    public ObString(string data)
    {
        _data = data;
    }
    public ObString() { }

    public void Add(object item)
    {
        _data = item.ToString();
    }
}
}