Warren, that theme had plenty of validation errors in it right out of the box (as do a lot of good-looking themes out there) so considering you got your site working decently in Mac IE 5.2, you’re doing great.
I, too, am a newbie at this stuff and have been learning things the hard way. The best approach I’ve found to fix what’s wrong with a site is to hack away at each validation error step-by-step. I don’t know if you know how to do that–but try this:
While viewing and working on your site in one window, open this link in a new browser window. It’s the “detailed” validation service, which is a little easier to work with than the simpler one.
Plug in your site URL and click the “show source” box and “validate this page.” It’ll show you all the errors you have (you’ve got 110 now). Start with the first one and work your way down.
It’s tedious, but it works, and sometimes fixing one error will fix a whole bunch, so it might not take as long as you think. That’s what we geek wannabes have to do to fix a site, rather than enjoy the miraculous blasts of talented digithead insights that save real geeks from borked themes.
The validator says your first error has to do with a missing html tag, so put that baby back in there right where you found it. I mean this one:
<html xmlns="https://www.w3.org/1999/xhtml" xml:lang="en" >
If it needs to be corrected, either some other helpful WordPress geek will tell you, or the validator will tell you, or whatever.
Save your changes on your site, then go to the other window with the validator in it, and hit “Revalidate” and see what happens.
Each error will have an explanation and a quick-jump link that’ll show you the actual code that’s in error. Sometimes the explanations will even make sense–if you have enough caffeine and sugar in your system.
So load up on the Skittles and go back to your site in the other window and fix it the problem. And from one geek wannabe to another, hang in there, because your site is looking good.