Urgent:centering a caption

Hi,
  I want to centre align a caption of a figure in a minipage.  
Please replace your figures with your own. 

Here is the tex code:

\documentclass[english]{prosper}
\usepackage[T1]{fontenc}
\usepackage[latin1]{inputenc}
\usepackage{graphicx}

\makeatletter
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Textclass specific LaTeX commands.
 \newtheorem{theorem}{Theorem}% Hack, define theorem, needed by theorem.inc
 \newtheorem{proof}{Proof}% Hack, define proof, needed by theorem.inc

 \newcounter{slidetype}
 \setcounter{slidetype}{0}
 \newcommand{\lyxendslide}[1]{
    \ifcase \value{slidetype}%
         \or % no action for 0
         \end{slide} \or%
         \end{overlay} \or%
         \end{note}%
    \fi%
    \setcounter{slidetype}{0}
 }
 \AtEndDocument{\lyxendslide{.}}

 \newcommand{\ov}[2]{\lyxendslide{.}\overlays{#1}{#2\lyxendslide{.}}}
\hypersetup{pdfpagemode=FullScreen}
\slideCaption{}
\mathversion{bold}
\usepackage{multirow}
\usepackage[dvips]{color}
\usepackage{babel}
\makeatother
\begin{document}
\begin{minipage}[c]{0.45\columnwidth}%
\begin{center}\includegraphics[%
  bb=150bp 300bp 420bp 542bp,
  clip,
  scale=0.6]{deform.ps}\end{center}\end{minipage}%
\begin{minipage}[c]{0.40\columnwidth}%
\includegraphics[%
  clip,
  scale=0.6,
  angle=-90]{uplot.ps}

\begin{center}DISPLACEMENT\end{center}\end{minipage}%

\end{document}



Need to do a presentation, so its a bit urgent(First time i will showing 
prosper to ppl here ;)


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