Did you try closing the quotes to see if it works?
Hey, whats that <font class="2"> doing in there? Why do you need to use <font> tag? Use <span class="2"> instead.
First step: get rid of all errors
Second step: improve the code by getting rid of deprecated elements where not required (eg. you may leave border for img, etc, but replce font class= with span class=)
Third step: Look for workarounds
I am quite sure its not IE5/Mac thing, its sloppy coding. Improper HTML will affect how the text looks. If your browser doesn't read <font class=" part of <font class="2">, how is it going to render the CSS?