Aligning Tables with CSS

Why will this not work in ANY of my browsers (MSIE 6.0, Mozilla 1.4, Opera 7.11, Netscape 7.1)?

table {
 text-align: center;
}

As you can see, I am trying to horizontally align a table. It will not work. I have looked through
documentation without avail for an alternative attribute, so instead I decided to randomly try
"horizontal-align" and "align", but these did not work either.

<table align="center"> works fine, but this is not valid in XHTML 1.1 or the XHTML 1.0 Strict DTD.

This is the page in question: http://eedev.palominoweb.com/

Furthermore the below works fine in MSIE 6.0 but not in Mozilla 1.4, Opera 7.11 or Netscape 7.1:

<div style="text-align: center;">
<table></table>
</div>

Confuzzeled,
- Damien