Using tables for navigation - is this acceptable?

I am trying to recreate a client's design so that is it accessible, but 
am struggling with my conscious with regards using a table for laying 
out some links.

I am working on the design at:
http://www.touchstone.org.uk/newdesign.html

Ideally I want the strip (multi coloured) menu along the top to stretch 
to fill the width of the screen with each menu 'block' being 
proportional to the text that it contains.

I have been playing around with a number of options, but the only way I 
can find of doing it is by using a table.

[I have been trying to persuade the client to accept that it won't 
stretch, but they would rather it did]

What would you recommend?

BTW - obviously the page still needs a lot of work doing to it to 
finish off the design as well as finalise it's accessibility.

Cheers,

Julian Voelcker
Cirencester, United Kingdom