Hello thelonius,
there is a package called "tabularx" (without the quotes of course ;-)).
the code could be something like this:
Code:
\documentclass[12pt]{article}
\usepackage{german,tabularx}
\begin{document}
\begin{center}
\begin{tabularx}{\textwidth}{|X|X|}
\hline
\raggedleft hello & world\\
\hline
\centering here & \centering I am
\cr
\hline
\end{tabularx}
\end{center}
\end{document}
hope this helps
robattack