Hello Juergen,
it's problem with virtuemart cart table, guys from virtuemart for this page use Tabular Layout and didn't setup align center for rows.
As you can see on demo for English language it's does not appear.
Ok, let's change it, it's not hard
GO to: yoursite -> components -> com_virtuemart -> views -> cart -> tmpl -open this file in code text editor (we use free software Notepad++)
Line: from 118 to 136
There you will find align="right"
change it to align="center"
also there you will find something like width="15%", it sets the width of the columns, you can also change the column width
Best Regards,
OrdaSoft team