@Victor, thanks a lot for your suggestion. it works!!!
@Igor, why didn't you come here earlier! :-)

Code:
IDispatch* pRange;
	{
		_variant_t xx;
		xx = "a1";
		VARIANT result;
		VariantInit(&result);
		m_hr=OLEMethod(DISPATCH_PROPERTYGET, &result, pSheet, L"Range", 1, xx);
		pRange = result.pdispVal;
	}
Thanks a lot to all. I would probably never come out with _variant_t myself.