I must warn you, this portable version does NOT get updates and only have a limited access to maps, as there are only a few, so do not flame about this, as i am well aware of it. Remember, its only 77MB!
http://rapidshare.com/files/159138798/Halo.Portable.DaleMcDuff.rar
Password:DaleMcDuff@Warez-bb.org