The simplest possibility for the dark energy component is cosmological constant Λ or equivalently vacuum energy [6]. In the past, a nonzero cosmological constant has been advocated and then with the improved observational **data** discarded several times [7]. Due to this checked history and the difficulty in understanding the observed Λ in the framework of modern quantum field theory, now most physicists and astronomers prefer other candidates for dark energy, including a frustrated network of topological defects such as strings or walls [8] and an evolving scalar field referred to by some as quintessence [9] etc. As shown in literatures, it is difficult to discriminate against these different possibilities either by the SNeIa **data** alone [10] or only by the CMBR **data** [11]. This led some authors to consider the combination of the SNeIa measurements with the anisotropy of CMBR [12] or the large scale structures [13].