latex multi-plots using minipage

\begin{figure}[h!]
\begin{minipage}{0.5\textwidth}
\begin{tabular}{c}
\includegraphics[width=\textwidth]{SPU64.eps} \\
(a)
\end{tabular}
\end{minipage}
%\hfill
\begin{minipage}{0.5\textwidth}
\begin{tabular}{c}
\includegraphics[width=\textwidth]{SPW64.eps} \\
(b)
\end{tabular}
\end{minipage}
\caption{Normalized streamwise velocity spectra (a) and vertical velocity spectra (b) at different heights obtained from $64^3$ LES. Numbers in plots denote normalized heights ($z/H$).}
\label{fig:SP64}
\end{figure}