Working on a singleton implementation

SingletonTemplate.hpp

namespace Utils
{
    template <class T>
    class Singleton 
    {
    public:
        static T& Instance()
        {
            if (MInstance == 0)
                MInstance = new T();
            return *MInstance;
        }
    private:
        // Data
        static T* MInstance;

        //Unique, Not Copyable
        Singleton<T>(const T&) {}
        Singleton<T>& operator=(const Singleton<T>&) {}
        ~Singleton<T>() {}
        Singleton<T>() { atexit(&Cleanup); }

        // cleanup
        static void CleanUp() { delete MInstance; MInstance = 0; } 
    };
  template< typename T >
	T *Singleton<T>::MInstance = NULL;
}

namespace Usage
{
    class Demo
    {
        public void SayHi() { cout << "Hi" << endl; }
    }
    typedef Utils::Singleton<Demo> DemoSingleton;
    void UseSingleton()
    {
        Demo& d = DemoSingleton::Instance();
        d.SayHi();
    }
}

Changed type of Demo, see http://stackoverflow.com/questions/14588143.