[XeTeX] Concrete fonts

[José Carlos Santos]

Hi all,

If I compile this file:

\documentclass{article}
\renewcommand{\rmdefault}{ccr}
\usepackage[T1]{fontenc}
\begin{document}
Some text.
\end{document}

with PDFLaTeX, then I get the sentence "Some text." typeset using the 
concrete fonts. However, if I replace the command

\usepackage[T1]{fontenc}

with

\usepackage{fontspec}

and I compile it with XeLaTeX, then the the font used is Laten Mdern. 
Why is that? And what should I do in order to use the concrete fonts?

Best regards,

Jose Carlos Santos