IE5/Mac woes and Alex King’s WP styles

I’m seeing minor problems that degrade to catastrophic ones using Internet Explorer 5 for Mac with Alex King’s WP styles.
I know that MSIE5 is broken. My question is, how broken? Do I write it off completely? Or are there quirks in Alex King’s styles which could be fixed to address these problems?
Details:
The styles in question are from Alex King’s WordPress CSS Style Competition, for example one called “Simple Sky”:
https://www.alexking.org/index.php?content=software/wordpress/styles.php
https://www.alexking.org/software/wordpress/styles/sample.php?wpstyle=simple_sky
https://www.alexking.org/software/wordpress/styles/wp-style/simple_sky/style.css
The minor problem is that IE5 screws up the horizontal position of the body of each post. Here are screenshots with IE5/Mac and Firefox 1.0:
https://aprendizdetodo.com/tmp/simplesky-ie5.jpg
https://aprendizdetodo.com/tmp/simplesky-ff.jpg
But there are bizarre and catastrophic behaviors as well. I find that trivial changes in content will cause IE5 to break the page completely. Specifically, adding certain lines of text in an

in the nav column will cause the whole nav column to drop down below the content column — but other text of comparable length won’t break it!
Here are pages that do and don’t break the placement of the navigation column. The difference between the two is a single character: the first contains the line “WordPress Wiki – How to combat comment spam with WordPress” and in the second the word “spam” is capitalized.
https://aprendizdetodo.com/tmp/simplesky-badnav.html
https://aprendizdetodo.com/tmp/simplesky-goodnav.html
Has anyone else seen this strange interaction between content and style in IE5?
P.S. Don’t tell me “get a better browser” — I use Firefox, but I can’t count on all of my readers to do the same.