Font size and accessibility guidelines

[alpha channel]

I am trying hard to make all sites now produced comply with the current accessibility guidelines and am fairly happy producing CSS that will work cross browser and on older versions.
However, one very basic question that I am getting mixed advice on.

I need to make all text resizable according to whats set up on the users browser and so that if necessary what I would like to see can still be overidden. I tend to make all text sizes in ems spinning off a basic size set in BODY in points.

Does that mean that the user in then constrained and unable to resize at will or does his default text size take precedence? Should I instead not constrain a basic size in points or perhaps use percentages? I would like to have some basic control, but dont want to overide the ability to resize for those that need it. I've read the full W3C guidelines, but it would be much more helpful to hear what those actually doing it out there use!!

[toicontien]

Text remains resizable if:

body { font-size: 12px | pt; }
div { font-size: 1em; } /* Assuming all text, and other elements that contain text,
                           are contained in a DIV */

And actually, I just set the body font size to 1em or 100%. I've run into an IE quirk when giving the body a fixed text size, and then setting your layout column widths in ems: The text remains resizable, but the layout doesn't grow or shrink.

I normally design sites with em-based column widths so that users can resize the text and the layout grows in proportion. (see http://mjw.cmich.edu/ for an example).

[alpha channel]

Thanks for that - I'll just set the basic size to 1em and then spin off from there.
Your site looks good by the way!

[toicontien]

Gracias!

[Robert Wellock]

Percentages, em or pixels are all fine - but some browsers are not.

[alpha channel]

You are telling me - biggest challenge to date - IE 5 for Mac - think I aged 5 years over that project!