Center tables in XEP print output

Hi all,

I'm desperately trying to center my tables using Saxon 9.1.0.2J and XEP
4.16. 

I tried to use the workaround available on
http://www.sagehill.net/docbookxsl/TableAlignment.html to get the
expected result but it didn't work correctly. 
It centers my tables but it compresses them horizontally and makes them
too narrow.

Then I tried to set the attribute 'wrap-option' to 'no-wrap' which
resulted in good looking small tables but too wide big tables.

I have made 2 screenshots - one where you can see the narrow tables, and
one with the wide ones. 

Just take a look at them here:
http://img22.imageshack.us/gal.php?g=tablewrap.jpg.

Any ideas?

Thank you in advance!

Greetings from Vienna, 

Mathias