  In this paper, we combine the latest observational data, including the WMAP
five-year data (WMAP5), BOOMERanG, CBI, VSA, ACBAR, as well as the Baryon
Acoustic Oscillations (BAO) and Type Ia Supernoave (SN) "Union" compilation
(307 sample) to determine the cosmological parameters. Our results show that
the $\Lambda$CDM model remains a good fit to the current data. In a flat
universe, we obtain the tight limit on the constant EoS of dark energy as,
$w=-0.977\pm0.056$ ($1 \sigma$). For the dynamical dark energy models with time
evolving EoS, we find that the best-fit values are $w_0=-1.08$ and $w_1=0.368$,
implying the preference of Quintom model whose EoS gets across the cosmological
constant boundary. For the curvature of universe, our results give
$-0.012<\Omega_k<0.009$ (95% C.L.) when fixing $w_{\DE}=-1$. When considering
the dynamics of dark energy, the flat universe is still a good fit to the
current data. Regarding the neutrino mass limit, we obtain the upper limits,
$\sum m_{\nu}<0.533$ eV (95% C.L.) within the framework of the flat
$\Lambda$CDM model. When adding the SDSS Lyman-$\alpha$ forest power spectrum
data, the constraint on $\sum m_{\nu}$ can be significantly improved, $\sum
m_{\nu}<0.161$ eV (95% C.L.). Assuming that the primordial fluctuations are
adiabatic with a power law spectrum, within the $\Lambda$CDM model, we find
that the upper limit on the ratio of the tensor to scalar is $r<0.200$ (95%
C.L.) and the inflationary models with the slope $n_s\geq1$ are excluded at
more than $2 \sigma$ confidence level. However, in the framework of dynamical
dark energy models, the allowed region in the parameter space of ($n_s$,$r$) is
enlarged significantly. Finally, we find no evidence for the large running of
the spectral index. (Abridged)
