\documentclass{article} 
\usepackage{c:/Programme/R/R-2.10.0beta/share/texmf/Sweave}
\usepackage[latin1]{inputenc}
%\usepackage[utf8x]{inputenc}
\usepackage[german]{babel}

\begin{document}
\begin{Schunk}
\begin{Sinput}
> Umlaute <- c("ä", "ö", "ü", "ß")
> Umlaute
\end{Sinput}
\begin{Soutput}
[1] "ä" "ö" "ü" "ß"
\end{Soutput}
\end{Schunk}
\end{document}
